Capo,
that is good advice, certainly on this list.

So my question

Is anyone planning to do up a short throat reamer in Northamerica? I leave again in a week, so I'm not the best middleman.

Would it be possible to have McGowen's reamer sent to Dave Manson to be modified to a ShortThroat? They could then add freebore as a client wished up to .5", ?, or 1.25".

quote:

Originally posted by 416Tanzan:
Would it be possible to have McGowen's reamer sent to Dave Manson to be modified to a ShortThroat? They could then add freebore as a client wished up to .5", ?, or 1.25".

Contact McGowen, should be possible... Anders Hatting (my gunsmith) have returned his reamer to Manson to have it modified to a .250" freebore...

gents - i would request that we settle on no less than .510 .. there are no advantages for going shorter and you WILL have vastly different results .250 v .510 ... as people found out when they, without fully thinking it through, went with short throated 300 weatherbies and had pressure excursions with FACTORY ammo ...


if we insist on a very short neck, even though the dies will be the same, let's call it something different --

I don't want THREE throats out there..

Call it a curr - Corey, Ulric, Rip redesign..

again, i do NOT fully believe the throat to be the issue, entirely, as we would see crazy pressures in some of the rubbish bullets i've shot through the 3 prototypes, including unbonded copper and core junker plinker bullets...

skidding is very different than drawing, in terms of action on the bullets..

again, i am pretty well set against a less than .510 neck, but you are free to call it whatever you like -- as long as it is acknowledged this is a variant/change from my original design.

taking an underbore fast twist high pressure cart to a short neck is a BAD design change, that compromises the optionality of the round. rip hasn't demonstrated a FACT, merely an opinion, in relation to use in a lower capacity case,

and rip has ZERO experience with the case in hand, and refuses to be involved as anything but a critic- -- and i am personally insulted by his continued "attention" in this matter, acting as if he is position to "teach" when, in fact, it is intention to preach. This isn't the first time he's began a tirade against cartridges I have designed, and lord-a-mercy THIS TIME there might actually be a grain of truth in his ranting.

I accept the design could possibly be better optimized -- I will not, however, be preached at by someone who presumes to act if these discovered facts are things he KNEW all along. not unlike michael moore commenting on politics --

Face it, guys, NO ONE, has ever seen bullets drawn like this, and hasn't ever entered into case design, as long throats were only thought to sometimes lead to inaccuracy. Gentlemen, we have discovered something NEW in the shooting world -- which is sort of unheard of in the last 75 years

Hi
Jeffeosso I will call it 500 Hatting

back to the reel life
godt the 500 barrel from Lothar Walther yesteday
I vill get the manson reamer back with in a week and the throat reamer fron PTG with in 14 days ( Ulrik must wait with a little more patience ) tihi

Ok…eliminating all discussion not relevant to the issue of P-S Freebore I’ll solely comment upon these four paragraphs.

quote:

again, i am pretty well set against a less than .510 neck, but you are free to call it whatever you like -- as long as it is acknowledged this is a variant/change from my original design.

1st it is your cartridge/chamber design specifications and you’ve obviously drawn the line in the sand.

quote:

taking an underbore fast twist high pressure cart to a short neck is a BAD design change, that compromises the optionality of the round. rip hasn't demonstrated a FACT, merely an opinion, in relation to use in a lower capacity case,

Last half first… The only capacity difference between the 500 AccRel and the 500/338 Lapua Magnum (aka: 12.7x68, 49-10) is the thinner walls of the Hornady case vis-à-vis the thicker walls of the Lapua case. Eliminate the case wall thickness – and the .510 caliber vs. the .500 caliber – and the cases are dimensionally virtually identical.

Now for the first half of the quote… Data and photographs pulled from page 5 of the Cutting Edge Bullets: 49-Bore/.500-Caliber/.338LM Improved of 2010 ... 12.7x68Magnum Thread
http://forums.accuratereloadin...043/m/5931027531/p/5

quote:

Also two of those CEB .500/500gr DGBR bullets, one showing the 3.503" COL/seating depth that worked well, feeds great in Winchester M70.
That CEB bullet length is 1.326".

Ok the trimmed brass length in the photograph is 2.647”; there is 0.470” of the bullet seated within the case neck and 0.856” of the bullet exposed. Now for the uninitiated, the length from the upper edge of the top band to the meplat is 0.563” in length so in the picture shown the upper edge of the top band is 0.293” above the case mouth and all bands on this bullet are 0.500” in diameter. Now the chamber specification for the 500/338 Lapua Magnum (aka: 12.7x68, 49-10) is:
Length to Neck Chamfer: 2.669”
Neck Chamfer Angle: 45º
Neck Chamfer Height (Length): 0.0145”
Parallel-Sided Freebore Length: 0.252”
Length from Neck Chamfer to Bore Diameter: 0.4958”
Length of Throat: 0.2293”
Throat Angle: 1º30’
So what all this means is:
Length to Start Throat Angle: 2.9335”
Length to End Throat Angle: 3.1648”
And for the loaded cartridge:
Loaded length to the upper edge of the upper band: 2.940”
Length of the upper band chambered within the throat: 0.0065”

I presume this should qualify as an example of the “compromised optionality” of the “short throat design” .

So to answer that question perhaps this additional data extraction and photograph will answer the question:

quote:

The 49-10 Saga creeps along.

The rain held off and the temperature abated to a balmy 84 F at start and 88 F at finish. Skies were sunny/cloudy, wind of no consequence.

First 4 shots to get on paper at 50 yards with the 92-grain charge of Benchmark, with the 500-grain/.500 caliber CEB DGBR FN solid.

I like to limit myself to 20-shots between barrel cleanings.
That's how I break them in.

Test fired yesterday for brass full-formed:



The 94-grain load gave 2381 fps and 0.401" at 50 yards, ought to be close to 0.8 MOA for three shots.

97-grain load gave 2473 fps, 0.637", about 1.3 MOA.

So we have 2381fps with excellent accuracy and 2473fps with typical OEM accuracy and no noted signs of pressure issues with the cases or primers for either loading. Unfortunately RIP recovered no bullets so he can’t provide proof of zero band abrading at this velocity with this chamber configuration.

But pulling a few photos from page 103 of the Terminal Bullet Performance Thread will resolve the band abrading issue with Michael’s 500 MDM…

with an impact velocity greater than the problem velocity identified by Hatting and Ulrik.

quote:

Face it, guys, NO ONE, has ever seen bullets drawn like this, and hasn't ever entered into case design, as long throats were only thought to sometimes lead to inaccuracy. Gentlemen, we have discovered something NEW in the shooting world -- which is sort of unheard of in the last 75 years

A 2+ caliber P-S Freebore pretty much went out of vogue in factory chambered rifles not to many years after the introduction of the 458 WinMag. Look at the modern high velocity BB DG cartridges such as the 416 RemMag or the 416 Ruger and you are looking at approximately ½-caliber P-S Freebore factory specifications…

quote:

I don't want THREE throats out there..

My recommendation for the three specifications was to accommodate the 1.25” P-S Freebore chambered rifles already in use – especially those in Australia – by shooters who may or may not desire to re-barrel using one of the two shorter freebore specifications...

Well I'm off to roost now...

Anders - that would be fine and the dies would work with any of the cases. I think you will see pressure excursions with the very short neck

Jim
Thanks for being patient with me
1 the Long throated design went out of vogue ( except for weatherbies) due to perceived accuracy issues and bad press. No one has ever seen sheeted off bullets from a long and bore sized throat. In fact long forcing cones on shotties and Taylor throating for pistols have been called accuracy improvers and recoil reducers. Shaved bullets are only seen in undersized revolver throats and WITH ALL BULLETS

2 rip's well thought out .500 round is very close in concept though I don't believe he copied me. I believe form follows function. The bullet catalog for .500 and .510 are very different. The .510 has to deal with 100 years of bullet designs and everything from 250 gr to 750 gr with sticky as all get out woodleighs being then hallmark. The .500 has a much narrower range and almost all of the bullets for it are STUBBY due to the majority of all these bullets must also work within the 500 pistol cart length. There are exceptions to that but the majority of those bullets are short in ogive regardless of maker. Therefore the niche bullets of .500 bullets has several design results and constraints that aren't relevant to a crossover
Design. This isn't talking out of my armpit as my ACTUAL 49 caliber design (which I am paying for the tooling to have a "legal" 49 caliber) has a different throat length do to short bullets being the norm in that space. Resized .500 bullets

3 I am interested in taking the feedback of folks. I am also not interested in over correcting and ruining the rounds top end performance.


I do appreciate all of y'alls good intention constructive feedback. I am
Listening. And for those that have to have the shorter neck I am reasonable in solution. I also don't believe .250 is a good length of neck with this design
But I could be wrong.

quote:

Originally posted by jeffeosso:
Anders - that would be fine and the dies would work with any of the cases. I think you will see pressure excursions with the very short neck

Jeffe - sure there will be a pressure rise compared to the 1,25" freebore barrel, BUT .250" freebore should give no problems I think - it will just give the same velocity with less powder. Maybe more like what QL predicts I quess... I had to go to a faster powder than first thought (VVN 530) to get the desired velocity (2300 fps @ 570 grs bullet) in the 1,25" FB barrel. Norma 202 with a heavily compressed load was unable to get much above 2200 fps..
After all RIP`s 49-10 and Michael`s 500 MDM have no issues at all with their .252" and .375" throats respectively.. And in my 500 AR 95% of the bullets fired will be either Barnes Banded Solids, North Fork FPS, GS Custom FN`s and CEB BBW#13`s.. The rest will be Hornady DGS solids and CEB non cons...

My 416 Wby has a .239" freebore and have never caused me any issues with excessive pressures. With all available bullets.. And I load it to 2800 fps with 400 grainers.. ... Follows QL quite accurately.. I don`t see why the 500AR should be different, but we will test and see, otherwise we just increase the FB up to .300" or .375" .....

Ulrik
It may very well be the case that you shooting very modern bullets would have little trouble at .250. However I feel that is too short for safety and this isn't meant to be a bench rest round. Half a caliber is too short my friend, but a custom throat is within your "rights" and i accept that

However, as the cases designer, half a caliber is too short for general use and i wouldnt be interested in changing the overall dsign to be that short. The case is underbore and there are huge bullets available

quote:

Originally posted by jeffeosso:
Ulrik
It may very well be the case that you shooting very modern bullets would have little trouble at .250. However I feel that is too short for safety and this isn't meant to be a bench rest round. Half a caliber is too short my friend, but a custom throat is within your "rights" and i accept that

If the 416 Rem and 416 Ruger are around .25" parallel freebore as Capo mentioned, then 0.25"
freebore in the 49-10 and potentially a 500AccR would not be unsafe, just different. It would only be unsafe in a MAX load for a 1.25" freebore that was fired in a 0.25" freebore. I have yet to see where a max load would go with the current 500AccR. The 1.25" freebore is out of my experience though I can extrapolate from what I've read. In the pre-60's heyday of freebore it sounds like 2 and 3 calibre freebores where often getting 150-200 fps increases. That is like the increase between a 338WM and the 340 Weatherby. In our terms, that may be like taking a 500AccR (shortthroat) and giving it the capacity of a 500Mbogo. Since the 500Mbogo should go beyond a 460Weatherby by virtue of having a similar capacity with a bigger bore, and since the 460 can generate 8000 ftlbs. that means that a 500 Mbogo should, and does, generate over 8000 ftlbs. So I conclude that the long freebore 500AccR can be expected to generate 8000 ftlbs safely. Since RIP's 49-10 short throat is already generating over 7000 ftlbs safely, I conclude that all of the current results on AmmoGuide will be safely duplicated in a shortthroat 500AccR, THOUGH WITH SLIGHTLY LESS POWDER CHARGES. Current powder listing would increase velocities accross the board in a shortthroat version.

anyway, one item that might be worth pursuing is to find out where the current MAX levels are for the 500AccR. Can anyone flatten a primer? Is there some dynamic at these larger sizes that would make a flat primer exceptionally dangerous?

quote:

Jeffeoso:
However, as the cases designer, half a caliber is too short for general use and i wouldnt be interested in changing the overall dsign to be that short. The case is underbore and there are huge bullets available

I'm not so sure that the 500AccR is 'underbore'. Granted, the shoulder is not large, but it has a shoulder. And many big bore rounds have no shoulder at all. The 500AccR reaches a comfortable/manageable level of recoil and I don't want to carry around a MAX-loaded Mbogo or an underloaded 50BMG. I think of the 500AccR as the efficiency king of the 50-calibre, something like the 308 for 30-cal. As I've said many times, and as I think Jeff implies in his AmmoGuide write-up, he was only looking for something at the level of factory 500Jeffrey and 7000 ftlbs slightly outdoes that. If a 500AccR safely and easily reaches a 7000 ftlb level then it does everything that we are asking of it. RIP has shown that his 49-10 safely exceeds 7000ftlb.

So I conclude that the 500AccR capacity design is EXCELLENT. It safely and efficiently does everything that we could ask of it. If someone wants more horsepower than a 7000ftlb 500AccR, let them build a full Rigby case 500 Mbogo//~510 Wells//~A2. the extra 1/4" of case will allow 8500 ftlbs but will require a longer action and a heavieer rifle.

For my needs, the 500AccR, shooting all the best hunting bullets, is about as good as it gets.

I thought before I reentered today’s discussion that I would explain the bullet/chamber drawings that I posted on July 31st…

The program that I used is QuickDESIGN and I specified the use of the CIP chamber specification.

The CIP chamber specification is why you see two angles noted – one 90º and one 40º00’32” – which relate to the neck chamfer angle and the shoulder angle respectively; CIP adds both sides of the angle while SAAMI only uses one side of the angle. Here is how they relate:
Neck Chamfer Angle: CIP = 90º and SAAMI = 45º
Shoulder Angle: CIP = 40º00’32” and SAAMI = 20º00’18”

Also I must again state, I do not possess a copy of the actual 500 AccRel finish reamer print so the chamber dimensions that I posted used the following known information to extrapolate the chamber dimensions:
Known – Jeffe’s posted cartridge specification
Known – the verified 1.25” P-S (Parallel-Sided) Freebore specification
The assumptions that I used were – the QD minimum chamber to cartridge clearance requirement specifications, the use of the standard CIP 90º/SAAMI 45º Chamber Neck Chamfer Angle, and the use of 1º30’ Chamber Throat Angle.

I’m more than will to correct any of this noted chamber information should the actual data be sharable… If not, then what I used is what I’ll use.

Now for the bullet – the 650gr .510 Ball M33 – a milspec/milsurp bullet…the bullet OAL is known and the BT length is known, what was estimated was the actual diameter of the bullet shank, the small diameter of the BT, the P-S shank length, and the ogive length (which is dependent upon the actual P-S shank length). If anyone can provide these exact dimensions I can redo the QD simulated bullet and correct the posted diagrams.

Also, I someone would provide the dimensions for one of the 3 .510 caliber Woodleigh FMJ bullets – the 600gr, the 570gr, or the 535gr – I’ll provide similar bullet/chamber diagrams for the 500 AccRel using that specific bullet or bullets.

Thanks,

Ok now on to today’s discussion which has forced me to move from my iPad to my laptop so that I could access additional information…quickly. And, I do apologize for the length of this post and I sure hope none of the information gets lost due to its length…

Jeffe I appreciate the discussion as well… Thanks. If we can keep it fruitful perhaps the 500 AccRel users, as well as yourself, can agree upon the Short Throat P-S Freebore specification and any Long Throat P-S Freebore specification should there be any change from the current 1.25” P-S Freebore specification.

Ok, let me be more specific regarding the CIP/SAAMI P-S Freebore for the .416’s including the Taylor…
.416 RemMag:
Length of P-S Freebore: 0.200” (48.07% of caliber)
Length from Neck Chamfer to Bore Diameter: 0.3126”
Throat Angle: 3º00’00”
.416 Rigby:
Length of P-S Freebore: zero
Length from Neck Chamfer to Bore Diameter: 0.300”
Throat Angle: 0º54’36”
.416 Ruger:
Length of P-S Freebore: 0.200” (48.07% of caliber)
Length from Neck Chamfer to Bore Diameter: 0.3853”
Throat Angle: 1º30’00”
.416 Taylor:
Length of P-S Freebore: 0.200” (48.07% of caliber)
Length from Neck Chamfer to Bore Diameter: 0.3126”
Throat Angle: 3º00’00”
So when I stated, “approximately ½-caliber P-S Freebore factory specifications” the actual value is slightly less at 48.07% of caliber. And, at least from my perception, the .416 caliber has the longest commercially manufactured C&C and CNC machined monometal bullets in the BB DG hunting bullet arena…

Now much has been discussed regarding the extra velocity/lower pressure that a ‘long P-S Freebore’ affords… Let’s see how the factory ‘freebore king’ fairs related to its ‘predecessor’ and the ‘new kid on the block’…:
.375 Weatherby:
Cartridge OAL: 3.600”
Case Capacity: 105.0gr H2O
PMap: 63817psi
Length of P-S Freebore: 0.7551” (201.36% of caliber)
Length from Neck Chamfer to Bore Diameter: 0.952”
Throat Angle: 1º05’20.04”
.375 H&H:
Cartridge OAL: 3.600”
Case Capacity: 95.3gr H2O
PMap: 62336psi
Length of P-S Freebore: zero
Length from Neck Chamfer to Bore Diameter: 0.3508”
Throat Angle: 2º00’02.88”
.375 Ruger:
Cartridge OAL: 3.340”
Case Capacity: 99.0gr H2O
PMap: 62004psi
Length of P-S Freebore: 0.1248” (33.28% of caliber)
Length from Neck Chamfer to Bore Diameter: 0.335”
Throat Angle: 1º30’00”
Ok..’historically’ the .375 Weatherby has been identified as producing approximately 240fps additional velocity over the same bullet weights in the .375 H&H. My question is how much of that velocity gain is due to an additional 9.7gr H20 case capacity plus an additional 1481psi PMap loading??? vis-à-vis the ‘long P-S freebore’??? I personally believe a major chunk of this extra velocity is due both to the additional case capacity and the higher factory loaded pressure level and very little to the long P-S Freebore specification.

Now overall bullet length… Yes the factory available bullets in .500 caliber are shorter in length as they are manufactured for use in the factory revolvers… That said, yes there is a great span of factory available bullet lengths and weights for the .510 caliber BUT those very long and very heavy for caliber bullets are designed specifically for use in the 50 BMG…not in the 500 Jeffery or the 500 Nitro Express so that’s kind of an ‘apples vs. watermelon’ comparison… So looking at the ‘apples vs. apples’ comparison – this being major brand hunting bullets – here is what we have bullet length wise:
.509/510 caliber Bullets – Principally Designed for the 500 Nitro Express:
700gr Barnes RNSP = 1.398”
600gr A-Square Mono RN = 1.300”
600gr Barnes Solid RN = 1.506”
600gr Woodleigh FMJ = 1.396”
570gr Barnes BND SLD = 1.700”
570gr Hornady DGS = 1.540”
570gr Woodleigh Hydro = 1.426”
570gr Woodleigh FMJ = 1.336”
.509/510 caliber Bullets – Principally Designed for the 500 Jeffery:
600gr Woodleigh FMJ = 1.396”
570gr Woodleigh Hydro = 1.426”
535gr Barnes BND SLD = 1.315”
535gr Woodleigh FMJ = 1.267”
525gr Barnes RN Solid = 1.310”
500gr GS Custom FNS = 1.240”

So let’s look specifically at these two factory cartridges:
.500 Nitro Express 3” CIP Specifications:
Cartridge OAL: 3.750”
Case OAL: 2.999”
Difference Between Cartridge OAL and Case OAL = 0.751”
Case Capacity: 138.00gr H2O
PMap: 40610psi
Length of P-S Freebore: zero
Length from Neck Chamfer to Bore Diameter: 0.3866”
Throat Angle: 0º53’58.99”
.500 Jeffery Rimless CIP Specifications:
Cartridge OAL: 3.468”
Case OAL: 2.752”
Difference Between Cartridge OAL and Case OAL = 0.716”
Case Capacity: 165.26gr H2O
PMap: 46412psi
Length of P-S Freebore: zero
Length from Neck Chamfer to Bore Diameter: 0.4098”
Throat Angle: 0º47’53.02”

Ok… What does the above information tell me? Simply that regardless of the bullet overall length, that each is designed to have <0.800” exposed portion of the seated bullet – as designed by each manufacture to meet the specific CIP cartridge specifications. Nothing more, nothing less… So from my prospective that’s the data we needs to paid attention to when discussing the proper P-S Freebore for the 500 AccRel using available commercial DG hunting bullets… which typically means <0.800” exposed portion of the seated bullet.

And again thanks to Michael and the Terminal Bullet Performance Thread, page 161, we see just how the Woodleighs engrave in Michael’s 510 Wells:
[




Now let’s look at the CNC monometal DG bullets available in .500 caliber for the 500 MDM and 500/338 Lapua Magnum (aka: 12.7x68, 49-10)…
550gr Lehigh Copper FN Solid = 1.431”
510gr Lehigh Copper FN Solid = 1.233”
550gr CEB BBW#13 Brass FN Solid = 1.493”
500gr CEB BBW#13 Brass FN Solid = 1.331”

So there we go standard SD computation wise – the 550gr .500 caliber bullets match the 570gr .510 caliber bullets while the 510/500gr .500 caliber bullets are slightly less than the 535gr .510 caliber bullets. The lighter weight Lehigh, CEB and NF FN Solid bullets (& their paired HP or CP NonCons) are designed for use in the shorter WSM and WSSM length rifle action and relating B&M cartridges.

Now… Just so no one thinks that Sam and Michael haven’t tested really long monometal bullets in the .500 caliber, again here are some photographs pulled from page 108 of the Terminal Bullet Performance Thread:

quote:

Now, speaking of Hollow Base Bullets--remember the ones Sam sent down before leaving, the ones that were going to beat Corbins little 6.5 pills?




Yes, well, I only had one each of those. I suppose I was too conservative on the load, and velocity was too low on both of them, so penetration was limited by velocity on this test--remember what I said about those "Other Days", this was today!





I see I typed in the wrong weight on the label too--Should read 540--Not 530 gr. Appears that day is continuing!
Michael

Now just eyeballing the 600gr .500 SAM BBW#13 HB FN Solid against the 50 B&M with 500gr .500 CEB BBW#13 Brass FN Solid – it appears the 600gr’r is about 2.275” long in a purely CNC banded bore-riding bullet design so that length and SD wise it’s in the same length SD category as the .510, 647gr .510 Speer FMJ BT BMG 2491 bullet @ 2.290” length and the 645gr .510 Speer FMJ BT 2491 @ 2.289” length bullets. Heck, move that HB into a HP and use the High-BC Talon Tip insert and length wise the 600gr .500 SAM BBW#13 moves into the 3.25” bullet length category of bullets…

Now in case anyone has forgotten, Michael’s 500 MDM is spec’d with a .375” P-S Freebore and that is primarily due to his initial monometal bullets being of the non-banded long shank RN and then FN bullet design style… Regardless, all of the current class of CNC machined DG monometal bullets work equally well in RIP’s 0.252” P-S Freebore (50.40% of caliber) and Michael’s 0.375” P-S Freebore (75.00% of caliber)…

Now I’ll throw something new against the wall to see if anything sticks regarding the issue of short vs. long P-S Freebore… And that something is gunpowder!

In Roy Weatherby’s heyday with his long P-S freebore design specification handloaders did not have the range of powder burn rates that we have in 2012. Cartridge factories could specify their burn rate/velocity specifications needs and the powder manufacturers would bulk blend their various powders to meet these specified needs. Inversely the handloader was bound by the powder burn rates commercially available in their market areas while simultaneously cautioned against attempting to blend various available commercial powders to meet a specific burn rate/velocity specification not otherwise available.

Now correct me if I’ve misunderstood this entire scenario but much of what I’ve read over the past 40+ years – that being that lengthening P-S Freebore allowed the use of more (a higher volume) of a slower burning powder which should increase velocity while reducing chamber pressure – was to overcome the lack of a proper burning powder that would produce the desired velocity range while keeping chamber pressure levels either down or at least within PMap specifications.

Today we have the opposite scenario – the various powder manufacturers have delivered the handloader a very wide variety of powder burn rates and generally the internet has made all of these powders available to the handloader so that the specific cartridge/bullet combination for can be optimized for 100% burn rate/maximizing muzzle velocity regardless of what barrel length that cartridge/bullet combination is used with – and often there are multiple powders that will satisfy the handloaders desired specification.

So with consideration to modern gun powder burn rate availability vis-à-vis to the range of powder available in Roy’s heyday of cartridge design specification…just how much of the ‘long freebore’ used by Roy and by many of the ‘long freebore’ handloaders was in response to the commercially available powder burn rates?

No attempt to argue the issue one way or the other…but if the modern powders available today eliminate the need for long freebore specifications made famous, or infamous, by Roy Weatherby do we need to both acknowledge this and move away from long freebore specifications? And by this question I’m not referring to the use of extra-long bullets that regardless of caliber will require a longer freebore specification to chamber the cartridge/bullet combination.

Ok…I have some errands to run so will check back later…

quote:

Posted 07 August 2012 17:01

quote:

Originally posted by jeffeosso:
Anders - that would be fine and the dies would work with any of the cases. I think you will see pressure excursions with the very short neck

Jeffe - sure there will be a pressure rise compared to the 1,25" freebore barrel, BUT .250" freebore should give no problems I think - it will just give the same velocity with less powder. Maybe more like what QL predicts I quess... I had to go to a faster powder than first thought (VVN 530) to get the desired velocity (2300 fps @ 570 grs bullet) in the 1,25" FB barrel. Norma 202 with a heavily compressed load was unable to get much above 2200 fps..

I'm running into the same problem. I just finished trying to load up some H335 powder for an upcoming test with 570 grain TSX bullets. 98.0 grains had only produced 2200 fps and I would like to find something at 2300 fps and even 2350 fps. 2300 fps would be around 6700 ftlbs with the 570TSX and 2350 fps registers arounds 7000 ftlbs.

It turns out that 100 grains of H335 fills up a case but still allows the 570 grain TSX to be fully seated to the last groove with a slight compression. 101 grains of H335 starts to run out of space. I could seat the bullet to the last groove but only barely. The bullet wanted to stop seating just as the case mouth went 1/3 of the way across the top groove. It still had enough lip to take a rolling crimp, but the crimp felt different from the crimp over 80% of the top groove at 100 grains of H335.

Thus, at 101 grains of H335 I have run out of room with the 570 TSX. the COAL is 3.425" while the 100 grain load allows a seating of 3.410" COAL. Both loads should be considered compressed. Hopefully, I will get a velocity reading on these in a couple of days, but I do not expect much over 2300 fps. So it is a MAX load by capacity, and will probably not be a MAX load by pressure and velocity.

I do not plan on getting a faster powder, however, since these loads may prove to be a pressure MAX in a shortthroat barrel.

Jim,
You are mistaken on the .375 Weatherby throat and case capacity.
The old original 1945-year throat was 2X-caliber P-S free bore,
but as of 2001 Weatherby changed the throat to slightly less than 1-caliber free bore length: 0.3700" length of P-S freebore of 0.3756" diameter.
Norma-made brass for the .375 Weatherby holds more than 111 grains of H2O.
All of this is off the top of my head, burned into my brain, look it up, prove me wrong if you can.

I have both old long-throated .375Wby as well as the latest CIP spec .375 Wby.
The old long free bore is 100 fps slower and shoots horribly inaccurately compared to the new 1-caliber free bore.
The smallest 3-shot/100-yard group I ever shot in my life was with the latter, shorter throated .375 Wby: about 0.138" for group



No doubt, by simple "bore law" the 500 AccRel can slightly beat the energy production of the 12.7X68 49-10.

You showed the initial loads above for the 49-10 with 500-grainer.
Final choice loads for top power with 500-grain solids:

H-322 98.0 grains >>> 2561 fps >>> 7285 ft-lbs
Benchmark 100.0 grains >>> 2533 fps >>> 7126 ft-lbs

The 500 AccRel can beat that, and do it accurately, with the right throat.

RIP, nice shooting.

thank you for the load data on the 49-10.

I agree with you that by "bore law" the 500AccR will do a tad more. that is why I am tentatively rating the cartridge at 7300 ftlb.

A question remains--
have you tested the 49-10 to a level where you started flattening primers?
It would be nice to know wherever that level is in a shortthroated 49-10.

quote:

Originally posted by RIP:
Jim,
You are mistaken on the .375 Weatherby throat and case capacity.
The old original 1945-year throat was 2X-caliber P-S free bore,
but as of 2001 Weatherby changed the throat to slightly less than 1-caliber free bore length: 0.3700" length of P-S freebore of 0.3756" diameter.
Norma-made brass for the .375 Weatherby holds more than 111 grains of H2O.
All of this is off the top of my head, burned into my brain, look it up, prove me wrong if you can.

Yep I knew the 375 Weatherby data was the original specification but I couldn't find my SAAMI disc, QD hadn't been updated with the 2001 SAAMI specification change, and I was to darn lazy to search through your postings to find the new data. I however will update the data while preserving the original.

quote:

Originally posted by 416Tanzan:
RIP, nice shooting.

thank you for the load data on the 49-10.

I agree with you that by "bore law" the 500AccR will do a tad more. that is why I am tentatively rating the cartridge at 7300 ftlb.

A question remains--
have you tested the 49-10 to a level where you started flattening primers?
It would be nice to know wherever that level is in a shortthroated 49-10.

416Tanzan,
I pretty much quit pushing it at 63,000 psi estimation by QuickLOAD, when I finally got case capacity measurement right
and a proper estimation of start pressures with the brass (low start pressure) and copper (high start pressure) bullets.
There were no signs of excessive primer flattening, firing pin indent cratering, brass extrusion into extractor cut of bolt face,
nor any stickiness of extraction nor case head expansion.

With either standard, modern .416 Rigby based case, or .338 Lapua Magnum based case that should be good.
Either 49-10 or 500AR.

If one wants to go to 68,000 psi with the .338LM case, you can get more foot pounds, but that is not necessary.
I don't plan to try to find the excessive load, but let us know if you do.

quote:

If one wants to go to 68,000 psi with the .338LM case, you can get more foot pounds, but that is not necessary.
I don't plan to try to find the excessive load, but let us know if you do. Wink

H335 is probably too slow of a powder for me to get there with a long freebore.

But this does underline the relative safety of even a 0.25" freebore. if we keep things under 7300 ftlbs, no one gets hurt.

quote:

Originally posted by 416Tanzan:

H335 is probably too slow of a powder for me to get there with a long freebore.

But this does underline the relative safety of even a 0.25" freebore. if we keep things under 7300 ftlbs, no one gets hurt.

True.
True.

On the relative burnrate scale fastest to slowest, I like these:

70. Alliant RL-7
72. H4198
74. H322
80. Hodgdon BENCHMARK

and H335 is a tad slower:

81. H335

With your bigger bore and similar case capacity, you will need a tad faster powder than H335,
even when you get a shorter throat,
for similar SD bullets.
With the heavier bullets H335 should be pretty good,
but it is a ball powder, and not one of the Extreme powders.
I bet BENCHMARK (Extreme, extruded) would be great with 570-grainers in the 500AR.
Consider H322 (Extreme, extruded) and faster powders
for the lighter bullets.

quote:

Originally posted by RIP:

quote:

Originally posted by 416Tanzan:

H335 is probably too slow of a powder for me to get there with a long freebore.

But this does underline the relative safety of even a 0.25" freebore. if we keep things under 7300 ftlbs, no one gets hurt.

True.
True.

Again - I agree, I dont see why the 500 AR is any different than many other rounds out there..., .250" of freebore should work for all available hunting bullets in the 500 AR.. I dont consider it "unsafe"...

Ulrik .510 won't hurt a thing in accuracy without the additional risk of the .250. This isn't a bench rest round an it is underbore.

Jim yes anyone with a lathe can make exceptional bullets. But not generally available.

I am digging my heels in here guys. I firmly feel that .250 is too short and ask that if you throat shorter than .510 that you call it something else. It is underbore and needs longer throat.

Ask yourself this. How many times have you read about an interesting round that had to be longer throated
To get higher velocity? Not unlike the win 405 or the 375 win compared to 38-55.

If you shorten the throat too much you may have pressure excursions. That may mean blown primers or worse, as you are willingly the raising pressure Curve at/near the point of maximum pressure.

I think .250 is grossly unwise in this case. Please rethink this or call the resulting round a derivative of the ar. And not a 500 ar. I'd rather not have 3 throats and I will not go .250 throat lenth as I think that is at the cutting edge minimum. This isn't meant to be a hot house flower or range queen round

quote:

Originally posted by jeffeosso:
I am digging my heels in here guys. I firmly feel that .250 is too short and ask that if you throat shorter than .510 that you call it something else. It is underbore and needs longer throat.

I have no problem with a .510 throat, and we might very well end there. But please explain me WHY it NEEDS the longer throat when other rounds like 416 Rem, 416 Ruger, 416 Wby, 375 Ruger and many many others have a 50% of caliber throat or even less??? I am not a gunsmith so I dont understand why the 500 AccRel will give better performance with a .510" Freebore instead of a .250" ???
Thanks Jeffe..
All the best
Ulrik

What are you guys going to call the new cartridge?

Eliminating the baloney above:

quote:

Originally posted by jeffeosso:

I am digging my heels in here guys. I firmly feel that .250 is too short and ask that if you throat shorter than .510 that you call it something else.

Most of the commonly available .510-caliber hunting bullets are designed for 500 Jeffery and 500 Nitro Express.
Those are throated with just a leade and the chamfer at the end of case neck, the "collar" of the chamber leading into the leade.
Zero length of parallel-sided free bore.
And cases are usually trimmed 0.010" shorter than max spec. brass length: more slop for safety

IIRC I get about 0.340" of full diameter bullet projecting into my 0.250" P-S free bore length in the 49-10:
plenty of jump left for safety.
Jim may calculate it precisely from specs, but actual chamber produced by reamer involves some slop,
and whatever it actually is, it works well:

1. brass trimmed from 2.657" to 2.647"
2. chamber length tolerances usually allow about +.020" to +.030" for case stretch and spring-back on firing,
as well as a usual +.004" for neck brass diameter expansion and spring-back for bullet release on firing.
(I'll have too look at 49-10 reamer print.)
3. "collar" chamfer beyond the neck of the chamber (usually 45-degree per side, 90-degree cone angle), tapers into the chamber throat
4. P-S free bore
5. leade

But again - why is .250" freebore more "unsafe" or at least "not so good" as a .510" freebore with all available hunting bullets from Woodleigh and Hornady DGS to Barnes Banded and North Fork/GS Custom/CEB solids??? I dont get it..???
My head must be thick....

Well,
I don't consider the 500 Accurate Nyati to be underbore
with its 7300 ftlb safe-limit, 2.65" Rigby-based case and 0.25" of freebore. Straightwalled cases like the 458 Lott are underbore. Much larger-capacity 505Gibbs and 500 Jeffrey are underutilized and may therefore be considered overbore. 500 Mbogo//510 Wells/A2 is a nice upper limit of normal.

500 Accurate Nyati.
It has a ring to it. A benchrest buffalo round. (nyati is ki-Swahili for cape buffalo)

The name 'accurate' keeps the genetic line with Jeff's development, the name Nyati keeps it separate from longer throats and is appropriate for a 50 cal cartridge. BTW, my barrel from McGowen is labeled 500 A. R. (12) because of the 12" twist.

quote:

Originally posted by RIP:
What are you guys going to call the new cartridge?

Eliminating the baloney above:

quote:

Originally posted by jeffeosso:

I am digging my heels in here guys. I firmly feel that .250 is too short and ask that if you throat shorter than .510 that you call it something else.

Most of the commonly available .510-caliber hunting bullets are designed for 500 Jeffery and 500 Nitro Express.
Those are throated with just a leade and the chamfer at the end of case neck, the "collar" of the chamber leading into the leade.
Zero length of parallel-sided free bore.
And cases are usually trimmed 0.010" shorter than max spec. brass length: more slop for safety

IIRC I get about 0.340" of full diameter bullet projecting into my 0.250" P-S free bore length in the 49-10:
plenty of jump left for safety.
Jim may calculate it precisely from specs, but actual chamber produced by reamer involves some slop,
and whatever it actually is, it works well:

1. brass trimmed from 2.657" to 2.647"
2. chamber length tolerances usually allow about +.020" to +.030" for case stretch and spring-back on firing,
as well as a usual +.004" for neck brass diameter expansion and spring-back for bullet release on firing.
(I'll have too look at 49-10 reamer print.)
3. "collar" chamfer beyond the neck of the chamber (usually 45-degree per side, 90-degree cone angle), tapers into the chamber throat
4. P-S free bore
5. leade

IN MY SHOP IT IS NOW CALLED .500 HATTING

OK, if someone borrows your reamer in Europe they can build a 500 Hatting.

Who in North America is going to provide a 500 Accurate Nyati reamer? I leave in a week for several months.

500 Accurate Hatting

The throat is sort of like a hat that the "bullet head"
fits into.
Accurate Hatting.

500 AH

Maybe 500 AR-H for Hunter 500 AR-T for Tactical with the long loaded BMG bullets? H also for Hatting 500 ARH (not to be confused with AHR)

There is no "Tactical" reason for the 1.25" P-S free bore.
There is no earthly reason for such an abomination.

quote:

Originally posted by hatting:
IN MY SHOP IT IS NOW CALLED .500 HATTING

Fantastic! Best of luck! Its nice to see a good guy reach out and make the changes he believes in.

Looking forward to your results

quote:

Originally posted by RIP:
There is no "Tactical" reason for the 1.25" P-S free bore.
There is no earthly reason for such an abomination.

\\

Ron, I've never said a single harsh word about your concepts of cases - not one - no matter how far off base and weird they might seem to me, i am certain that somewhere, in your mind, there was a darn good reason for them. If something was far afield, i would send you a PM, if I thought it was a safety concern, otherwise, no matter how weird it was, it wasn't my place, as I had no skin in the game

This is called courtesy and respect of a peer --

no matter how misplaced, i believe in those as the grease that lets us all get along.

quote:

Originally posted by jeffeosso:

quote:

Originally posted by RIP:
There is no "Tactical" reason for the 1.25" P-S free bore.
There is no earthly reason for such an abomination.

\\

Ron, I've never said a single harsh word about your concepts of cases - not one - no matter how far off base and weird they might seem to me, i am certain that somewhere, in your mind, there was a darn good reason for them. If something was far afield, i would send you a PM, if I thought it was a safety concern, otherwise, no matter how weird it was, it wasn't my place, as I had no skin in the game

This is called courtesy and respect of a peer --

no matter how misplaced, i believe in those as the grease that lets us all get along.

To jeffeosso: HOGWASH!!!

Hell no, we do not stick our heads in the sand and ignore idiocy.
Can't fix stupid, but can fix the effects of it.

Gentlemen, gentlemen,

The 500 AccRel is the greatest stopping cartridge designed for a common boltaction rifle, let's at least be civil. The 49-10 is just as great, now that some rifle bullets are available.

416Tanzan,
Thank you for calling attention to how uncivil jeffeosso has become,
calling my ideas "weird and off base."

He has no defense for his 1.25" P-S free bore so resorts to campaigning like a Democrat.
No intellectual honesty. No good ideas. "Can't we just get along?"
Next thing you know he is going to be offering free birth control pills with his ream job,
even though you can get them for $7 per month at Walmart or Target,
and you don't have to bend over and grab your ankles for his ream job at that price.

My weird ideas on throat:

Minimum on the 12.7X68 49-10, initially called the 500 XXX: 0.252" P-S Free Bore



Maximum on the 500 Mbogo: 0.500" P-S Free Bore

No, Ron. You are being a jerk about this entire matter and I am tired of it. One doesn't attack as civil discourse. I have asked you repeatedly to be nice an you have refused. Mistakes have been made and corrected in my part. I am tired ad reached the end of my patience with your antics and have out up with them with a decent enough attitude. Going so far as to encourage people to try it their way when it goes past what I feel is a good design.

Thanks Corey. I think it is a good round and likely to be better when changed to perform with these cutting edge bullet designs. No one has ever seen these types of results before and it was unforseeable.

Jeffe:

Let us stick to technical issues. If I want touchy-feely it is sure not going to be on the "Big Bore" forum at AR.com.

Got your mind around that?

Technically speaking it is indeed time to move on, to a shorter than 3X-caliber overall throat.
and that time came long before CEB or any earlier brass bullets.
It never has been a good idea for any bullet ever made.

Ok guys, time to pull the stakes out of the sand.

Jeffe,
You are correct. You could not forsee that brass construction bore-riding bullets at 2200+ fps would result in abraded banding rather than engraved banding when you established the 500 AccRel chamber specifications.

Ron,
Thanks for posting the 500 Mbogo chamber print.

And now I have a couple of questions that may resolve Ulrick's need to putz with one barrel in various P-S Freebore lengths to satisfy the band abrading question.

Ron,
Have you fired the 570gr Barnes TSX or BND SLD bullets from your 500 Mbogo?
If so, do you have any recovered bullets - hopefully fired at +2200fps - from game, water buckets, dirt, etc.?
And perhaps long range targets using the 450gr GSC HV bullet? (closest match to the 430gr CEB MTH in the .510 caliber).
And finally, do you have any long range targets fired with the 570gr TSX bullet? Hopefully 200yd or 300yd...

Why all the questions? Very simple.
You have a 0.500" P-S Freebore specification in your Mbogo.
Jeffe wants a minimum 0.510" P-S Freebore for the revised 500 AccRel.
Tanzan and Ulrik could care less exactly what the 500 AccRel P-S Freebore is - they just want high velocity long range high velocity accuracy with hunting bullets and neither desire to use milsurp 50 BMG bullets.

Jeffe,
Yes, Ulrik and Tanzan want accuracy at least equal to Ron's 12.7x68/49-10 rifles. If a 0.500" P-S Freebore in Ron's 500 Mbogo doesn't deliver similar accuracy to the 12.7x68/49-10 cartridge then yes, the P-S Freebore needs to be less than 0.500" length.

Thank you Ron,

Jim,
Hatting and Ulrik are wised up!!!
No putzing required. 500 Hatting: .250" P-S sided free bore.

I used to shoot all sorts of bullets in .588" P-S free bore .510 JAB, I used to recover them from the IWBB, including GSC FN.
No band abrading issues, but I never got the fine accuracy in that throat unless I was shooting long target bullets seated out to fit the throat.
Something like 705-grain AAA Harlow bore riders would give sub 0.2" for 3 shots at 100 yards.

The 500 Mbogo .500" P-S Free Bore length for .510-caliber hunting bullets will do sub MOA, but not sub 0.2 MOA for 3 shots.
I never played with the long target bullets in the 500 Mbogo, having got those jollies off in 500 A2 years ago.

As a rule, the shorter the throat, the better accuracy possibility, due to being able to fit various bullets closer to the lands.

Here is an example (49-10) of finding the right seating length (and powder charge) for the 460-grain CEB NonCon,
as compared to the misbegotten 400-grain ESP:

(from 4-22-2012):



That long bullet seated out in the excessive .588" P-S free bored .510 A2 equivalent:

(from 4-20-2002, 10 years prior to the above):


0.500" P-S sided free bore or shorter for .510-caliber bullets will be more accurate than .588", but not as accurate with the hunting bullets of lighter weight, as something like a .250" P-S free bore length.

I have some old pics stored away, maybe, but
I am not able to go rummaging for old recovered bullets right now, but will keep an eye out for them.