Jim,
Re. stripping bullets in the extra-long throat:
Isn't that problem Barnes bullet made of brass, not copper (Barnes Banded Solid)?
The copper ones did OK, they have wide bands with multiple cannelures (like the TSX)
and plenty of grabby full-bearing copper surface.
The fancier minimal bearing copper bullets like the GSC HV and FN might not fare so well

Here is my throat rec. from 2006 when jeffeosso was designing the 500 AR:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Posted 02-20-2006 3:13 PM Hide Post
Jeffe,
I sure like the 2.7" best.
That would be unique.
Given a .5000" parallel-sided freebore length
and a freebore diameter of 0.5105" or 0.5110" (bullets are 0.509" to 0.510")
with 1.5 degree leade:

It could be used for any bullet and in all but the shortest of actions (seat long for 3.8" box, or seat short +/- trim brass 0.100" for the 3.4" box ... depending on the length of the bullet nose, etc.). That freebore would allow the use of any milsurp 50 BMG bullet and the Hornady 750 grain A-Max
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I was thunderstruck too when I heard about the final throat choice for the reamer,
and Ulrik taught us all something about the effects of a throat like that on brass bullets.

Here is the beautiful 500 AR cartridge loaded with a milsurp:



This one requires only about caliber-length parallell-sided free bore plus leade,
to give plenty of free bore,
for pressure control without velocity loss,
and good accuracy,
I am sure,
no need to measure.

I thought this was the most telling of the photographs:



Obviously no need for 1.25” P-S freebore to chamber the milsurp loaded round…

quote:

Isn't that problem Barnes bullet made of brass, not copper (Barnes Banded Solid)?
The copper ones did OK, they have wide bands with multiple cannelures (like the TSX)
and plenty of grabby full-bearing copper surface.

I thought that all bore-riding Barnes BND SLDs were were machined from copper? Edit Added: Oops just noticed on their website that they're a copper zinc alloy but no percentages given... So classified as copper? Or classified as brass? I don't know!

Ok killing a few minutes so went back through the linked threads, here’s where I found Jeffe’s reference to the 500 AccRel freebore; I edited out much of the post…

pics added - 500 AR – revisited
http://forums.accuratereloadin.../4711043/m/681106016

quote:

Originally posted by jeffeosso: [Posted 30 January 2007 06:56]
revised 2-1-07

…………………

So I have to thank Rich and Lawndart for the base brass. Funny enough, the 338 Lapua and 416 basic (LD and ISS) measure DARN CLOSE to the same neck thickness

I am thinking a 1" leade, to allow milsurp bullets

firstly, these are ROUGH formed, literally using my 500 jeffe dies, and yeah, they aren't exactly the same

second, this is with a .561 shoulder, (as formed) final will have a .577 shoulder, or MORE than 25% improvement in headspace..

third, the base diameter on Rich's cases are right at .586 +/- .0005

cases weight 322.00gr, and as drawn, that makes them 131 gross water capacity... making it ~1% smaller than the 495 A2, which means 1.25% LESS velocity than the 495A2, at the same pressures... (.495 SAYS it runs a 600gr at 2360.. okay, if you believe that, then the 500 AR will do that at 2350ish)

…………………

2.65" case, 3.4 OAL MAX

…………………

Brass = copper-zinc alloy
Bronze = copper-tin alloy

That is the basic scheme, though traces of lead, etc. are also in both brass and bronze of various sorts.

Barnes "banded solids" are brass.

I think the final dimension was set when MRC set the final magazine length of the mag well on the PH. I don't know if that would be in Big Bores or Gunsmithing as there were PH threads in both. By doing that we got the absolute max powder capacity to get above 2000 fps with mil surps. Building the reamer around mil surp shooters is playing to a really small minority but that's how it came about. We were blowing a lot of stuff up with Tannerite at the time and things that went "BANG" were in vogue.

quote:

Originally posted by tiggertate:
I think the final dimension was set when MRC set the final magazine length of the mag well on the PH. I don't know if that would be in Big Bores or Gunsmithing as there were PH threads in both. By doing that we got the absolute max powder capacity to get above 2000 fps with mil surps. Building the reamer around mil surp shooters is playing to a really small minority but that's how it came about. We were blowing a lot of stuff up with Tannerite at the time and things that went "BANG" were in vogue.

TT,
I definitely understand the rational – I just think the specs went overboard with the freebore…

quote:

500 ar+bmg bullet 4.155 long - COULD fit in a PH action

Excerpt from post by jeffeosso: (Posted 12 October 2005 15:28)
416, 458, 470, and 500 AR - the line of AR rounds - dialup warning thread
http://forums.accuratereloadin...1043/m/769108843/p/1

And:

quote:

The third action in our line of actions is the Professional Hunter Action. It is currently in production and we have begun to ship the Chrome Moly actions!

This action will handle any cartridge from the 338 Lapua up to 505 Gibbs length cartridges.

Currently we are looking at a internal magazine length of 4.043".

Above quote pulled directly from the Montana Rifles website.
http://www.montanarifleco.com/...sional%20Hunter.html

Ok… I’ve zero idea what the Montana PH action’s internal magazine length finally comes out to but on the off chance that Jeffe’s 4.155” COAL is correct I did some work in QD regarding current 500 AccRel 1.25” P-S freebore and the identification of what would be the minimum P-S Freebore for the 650gr Ball M33 FMJ bullet to touch the lands…

So here are two pictures of a QD facsimile 500 AccRel, loaded with the 650 .510 Ball M33 FMJ bullet, loaded to a COAL of 4.155”:
1st – 1.25” Parallel-Sided Freebore and 2nd – 0.1926” Parallel-Sided Freebore

Where you see the measurement 0.2241” measurement on the right side – combination of the 45º chamfer length of 0.0135” length and the 0.1926 P-S freebore length - is the collision point between bullet and land.

So if a 0.1926” P-S freebore is the bullet/land collision point (assumption of 4.155” cartridge OAL using the milsurp 650gr Ball M33 bullet) just how much P-S freebore do you need to hit the sweet spot of accuracy, velocity, and chamber pressure???

Edit Added: Oops…guess I should give the following information for the facsimile 650gr .510 Ball M33 FMJ bullet that I generated in QuickDESIGN to produce the above prints:
Bullet Overall Length: 2.310”
Boattail Length: 0.386’
Length to Shank/Ogive Intersection: 1.060” (This was a WAG to add 0.300” P-S Shank beyond 50 BMG normal seated depth of 0.760”)
Bullet Diameter: 0.510”

Q: "So if a 0.1926” P-S freebore is the bullet/land collision point (assumption of 4.155” cartridge OAL using the milsurp 650gr Ball M33 bullet) just how much P-S freebore do you need to hit the sweet spot of accuracy, velocity, and chamber pressure???"

A: A lot less than 1.250",
and in fact you will be hard pressed to find any milsurp or Hornady A-Max that requires more than caliber length free bore,
forget about two-and-a-half times caliber.

If .250" of freebore works so well in the 49-10 - why shouldnt it work equally well in the very similar 500 AccRel????

I surrender!

Guys. The only thing that will change my mind is the testing. I know we have an issue with a certain type of bullet, that I happen to really like. However the constant attacks and negative tone feedback in the design, 5 years after request for comment, isn't so helpful.

Could it be shorter? Certainly. How much shorter makes it work I. All MY design conditions? Let's actually have data rather than some feedback and some running off at the mouth, please.

I am not going to be an actor tit for tat participant on this thread, don't take silence for acceptance

quote:

Originally posted by buffalo:
If .250" of freebore works so well in the 49-10 - why shouldnt it work equally well in the very similar 500 AccRel????

1 mine was designed first
2 .500 bullets there arent or weren't any long range or heavy rifle bullets designed when I designed the 500
3 the 49-10 bullet supply is mostly short pistol bullets or was wen I designed the 500 ar

I don't believe is Long bullets and Short throats. I don't believe in bullets EVER touching the rifling in a hunting round. Less than caliber doesn't work formdesigns. And until we saw sheared bullets it didn't bother anyone else either. This is "genius after the fact"

quote:

Originally posted by buffalo:
If .250" of freebore works so well in the 49-10 - why shouldnt it work equally well in the very similar 500 AccRel????

Should work very well, Ulrik.
jeffeosso is calling you a "genius after the fact."
Jeffeosso did get my design input more than 5 years ago, before the fact, and ignored it.
I have been playing with .510-caliber bullets and throats since 1999.
It is very hard to out blow a hard headed blowhard ... I give up on the blowhard.

quote:

Originally posted by tiggertate:
I surrender!

Tiggertate has shown intelligence, an open mind, he learns!!!
We all learn and go on, hopefully.
Can't fix stupid.
Stupid throat should be abandoned.

TT,
Don’t surrender… We need to know from your prospective – one of the 500 AccRel users in the Montana PH action (use of max-COAL with milsurp bullets) – the COAL that you use as well as how your accuracy is at long distance.

Jeffe,
You are correct in that 3 of the 4 of us were not involved in the discussions regarding the P-S freebore for the 500 AccRel for a dual functional purpose… 1st as a .510 caliber hunting cartridge and 2nd as a .510 caliber cartridge alternative for use with 50 BMG milsurp bullets…

I’m not building a 500 AccRel but Tanzan and Buffalo have built rifles in this caliber and both desire recommendations on how to eliminate the band abrading of the brass bullet banding… I am solely attempting to help the two of them by providing some alternative solutions…

Now a comment regarding

quote:

I don't believe is Long bullets and Short throats. I don't believe in bullets EVER touching the rifling in a hunting round.

That was done to give everyone a benchmark of exact parallel-sided freebore to force the bullet and rifling to touch… Nothing more… Nothing less… However with that specific information it is very easy to identify the amount of P-S freebore required to 1) allow the maximum target COAL, and 2) to build in the optimal distance between the bullet and rifling for best accuracy and lowest pressure…

quote:

And until we saw sheared bullets it didn't bother anyone else either. This is "genius after the fact"

I don’t recollect reading in any of the various threads that discussed the 500 AccRel where any individual ran the Barnes BND SLD bullets above NE express velocities within which the brass banding does not abrade. So this issue would not have been identified until such time as the 1st individual upped the velocity sufficient to encounter the abrading issue. You refer to this as “genius after the fact”. Others might refer to this a “insufficient testing before the specifications were set”. Myself, I refer to the abrading issue as “a problem seeking resolution”.

So…looking at this entire situation as “a problem seeking resolution” I’ve delved into QD again this morning along with PacNor’s chamber print book so that I could give the pictorial renderings of the 50 BMG using the simulated 650gr .510 Ball M33 FMJ bullet…
1st is the 50 BMG – Browning – Machine Gun Barrel Specification, and 2nd 50 BMG – Frankford Arsenal/Cliffton – Accuracy Barrel Specification


So using the combination of the ‘chamfer angle length’, the ‘P-S freebore length’, and ‘throat angle’ that the smart folks at Frankford Arsenal, as well as Cliffton, I’ve adjusted the ‘P-S freebore length’ to accommodate the ‘length of the 45º modern chamfer angle’, to match the ‘smart guys’ chamber mouth/chamfer junction to the throat angle/bore diameter junction of 0.6251” length AND the same 1º19’ throat angle. And this is what I came up with:
Proposal - 500 AccRel – loaded with a simulated 650gr .510 Ball M33 FMJ bullet – COAL of 4.200”

quote:

Less than caliber doesn't work formdesigns.

I’m not sure what formdesigns is though I’m assuming it is a design program similar but different than QuickDESIGN. But… Ok let’s look at Buffalo’s proposed 0.250” P-S Freebore and the 1-Caliber P-S Freebore that RIP proposed 5+ years ago and that you note as the minimum that works in formdesigns…
Note both designs use: Simulated 650gr .510 Ball M33 FMJ bullet, a 1º30’ throat angle, and a 4.155” COAL
1st 500 AccRel ST – 0.250” P-S Freebore Specification, and 2nd 500 AccRel ST – 0.510” P-S Freebore Specification

So either of these two P-S Freebore specification works just fine with the 650gr Ball M33 FMJ milsurp bullet though the .510" P-S Freebore specification would be better for use with milsurp bullets. And either will work fine with the 570gr Woodleigh FMJ bullet though the 0.252" P-S Freebore specification is likely best for bore-riding monometal bullets.

Therein lies the problem. I think milspec on 50 cal APTI is something on the order of 2 or 3 MOA for acceptance so I never expected stellar accuracy to begin with.

I am fortunate in one regard (or lucky) in that I had my barrel profiled to 1.375" x 3" long (not including the threaded tenon) at the finished shank. That was for weight and to be somewhat proportional to the big action. So I have plenty of barrel to rechamber and re-throat when I run out of the thousand or so APTIs I have laying around. But then I'm not sure I'll be shooting many big bores when I'm eighty.

But I can upload a pic of my loaded rounds laying in the mag well of the PH. They're very close to the one in your picture which I think is a bit longer the drawings immediately above.

quote:

Originally posted by tiggertate:
Therein lies the problem. I think milspec on 50 cal APTI is something on the order of 2 or 3 MOA for acceptance so I never expected stellar accuracy to begin with.

I am fortunate in one regard (or lucky) in that I had my barrel profiled to 1.375" x 3" long (not including the threaded tenon) at the finished shank. That was for weight and to be somewhat proportional to the big action. So I have plenty of barrel to rechamber and re-throat when I run out of the thousand or so APTIs I have laying around. But then I'm not sure I'll be shooting many big bores when I'm eighty.

But I can upload a pic of my loaded rounds laying in the mag well of the PH. They're very close to the one in your picture which I think is a bit longer the drawings immediately above.

TT,

That's good info! What is your max. COAL that will feed from the PH action?

Also, what distance do you typically shoot...and what is your typical accuracy at that distance?

Thanks,

Jim,
Those are great drawings for reference. Thanks.




The black tip AP milsurps are excellent plinkers, weigh about 700 grains,
and are much more accurate than the APIT conglomerations of multiple compartments of varying densities and concentricities.

I have one more .510 caliber rifle to build.
It will use the take-off barrel from the original .510JAB that used an excessive .588" length of P-S free bore,
to more than accommodate COAL of more than 4.750".

I was not as smart in 1999.
Now I have a chance to cut 1" off the breech end of that fat barrel,
and have it rechambered with a shorter P-S free bore length.

The original throat specs of the 500 A-Square?
Either 0.350" or 0.400" of P-S free bore?
I can't remember off hand.
Wonder what the copycat 50 Peacekeeper used?
Don't think I ever saw that closely guarded proprietary secret.

quote:

The original throat specs of the 500 A-Square?
Either 0.350" or 0.400" of P-S free bore?
I can't remember off hand.
Wonder what the copycat 50 Peacekeeper used?

Picture me ‘shrugging shoulders’… No answers here.

Finally some interesting data for us to consider.

I was able to do some testing of the 570 TSX at about 2200 fps muzzle in the 500 AccR.

The velocity was lower than anticipated. That was due to interpreting the data on AmmoGuide where loads of 100 grains H335 with shorter lead-core 570 grain bullets already produced over 2300 fps. I thought that 2300 fps would be a reasonable hunting load with the 570 grain TSX. The TSX is quite a bit longer than other bullets so I figured that 98 grains of H335 and the TSX would produce similar velocities to the lead-core bullets. In my rifle this did not work out. Fine. 2200fps. I might load up TSX with 101 and 102 grains H335 to try and reach 2300 fps.

for accuracy I bedded the forearm lug in steel epoxy in order to help stabilize the Hogue stock. I also mounted a Nikon Slughunter Scope 1.65-5 in Ruger Extended mounts (front ring toward the rear and accommodating the rather compact Nikon scope. The scope did not move during testing.

However, the best group was only 2.2". I do not consider that worth playing with, in other words, the rifle has earned itself a trip back to McGowen Barrels. (Yes, there was a little breeze. But on the same afternoon the 338 WM shot sub-MOA groups with 175 grain tip-less Raptors. And the TSX has a much better BC than a non-con hollowpoint.

So what could be the cause of relatively poor accuracy? I think that even the TSX is skidding on the lands after too generous freebore. I recovered one bullet from a dirt berm. Careful inspection showed that it skidded straight the length of the bullet bearing surface before it engaged the lands and then showed rifling marks. The pictures below partially document this. the problem is the clarity of the picture.



In this first picture some of the brightness on the left side and left of center is from the skidding while the darker streaks coming up from the middle are part of the rifling. There are vertical lines in the bright ares that are visible when holding the bullet that suggest cuts from the rifling ridges in the leade area. See another view below.




In this picture the bullet is tilted with the base toward the camera. The rifling is visable from the base about 40% of the way from the left side. Some of the brightness to the left of this and some of the vertical streaking about 60% from the left side.

What I see is a bullet that is skidding so much that skidding might be considered a factor in less that tight accuracy. Could I hunt with this? Surely. But I did not go to all of the trouble of building a custom bigbore to have a rifle of 2"+ MOA. Our 416's can cover us while we figure out what to do with a 500 AccR. When McGowen has a short-throat reamer I will send them a rebarrel job. I'm happy with .25" to .375" parallel freebore + a leade of 1.5º-2.0º.

I hope my LW barrel arrive in August... Looking forward to do more testing...

quote:

Originally posted by 416Tanzan:
Finally some interesting data for us to consider.

I was able to do some testing of the 570 TSX at about 2200 fps muzzle in the 500 AccR.

The velocity was lower than anticipated. That was due to interpreting the data on AmmoGuide where loads of 100 grains H335 with shorter lead-core 570 grain bullets already produced over 2300 fps. I thought that 2300 fps would be a reasonable hunting load with the 570 grain TSX. The TSX is quite a bit longer than other bullets so I figured that 98 grains of H335 and the TSX would produce similar velocities to the lead-core bullets. In my rifle this did not work out. Fine. 2200fps. I might load up TSX with 101 and 102 grains H335 to try and reach 2300 fps.

for accuracy I bedded the forearm lug in steel epoxy in order to help stabilize the Hogue stock. I also mounted a Nikon Slughunter Scope 1.65-5 in Ruger Extended mounts (front ring toward the rear and accommodating the rather compact Nikon scope. The scope did not move during testing.

However, the best group was only 2.2". I do not consider that worth playing with, in other words, the rifle has earned itself a trip back to McGowen Barrels. (Yes, there was a little breeze. But on the same afternoon the 338 WM shot sub-MOA groups with 175 grain tip-less Raptors. And the TSX has a much better BC than a non-con hollowpoint.

So what could be the cause of relatively poor accuracy? I think that even the TSX is skidding on the lands after too generous freebore. I recovered one bullet from a dirt berm. Careful inspection showed that it skidded straight the length of the bullet bearing surface before it engaged the lands and then showed rifling marks. The pictures below partially document this. the problem is the clarity of the picture.



In this first picture some of the brightness on the left side and left of center is from the skidding while the darker streaks coming up from the middle are part of the rifling. There are vertical lines in the bright ares that are visible when holding the bullet that suggest cuts from the rifling ridges in the leade area. See another view below.




In this picture the bullet is tilted with the base toward the camera. The rifling is visable from the base about 40% of the way from the left side. Some of the brightness to the left of this and some of the vertical streaking about 60% from the left side.

What I see is a bullet that is skidding so much that skidding might be considered a factor in less that tight accuracy. Could I hunt with this? Surely. But I did not go to all of the trouble of building a custom bigbore to have a rifle of 2"+ MOA. Our 416's can cover us while we figure out what to do with a 500 AccR. When McGowen has a short-throat reamer I will send them a rebarrel job. I'm happy with .25" to .375" parallel freebore + a leade of 1.5º-2.0º.

Agree Tanzan - it doesnt look too good with the TSX`s either... I agree with your decision, no need for an inaccurate rifle and skidding bullets.. I dont care about the ability to shoot milsurps at all, but all hunting bullets has to work in my rifle. And work 100%. All the time.. No compromises accepted here.. No - I will have a short throat version asap. After all the 500 AccRel is very well designed, and I am sure it will work perfect when it has the appropiate throatspecs ...

In checking the .509" TSX bullets it turns out that they are actually .508" (.5079-.5081"). That, of course, could add to an accuracy problem.

So when listing all of the variables that may be leading to less-than-expected accuracy we can list:

1. 1.25" freebore
2. .508" diameter bullets in a .510" barrel
3. The bedding of the rifle. (It is a relatively new rifle in a stock whose bedding has never been verified as sub-MOA capable. Because of the Hogue design I have not touched the Ruger front lug area for fear of unbalancing the pillar and rubberized stock with epoxy that may not sufficiently grip the rubberized plastic. I did bed the CZ style barrel lug along the plastic interior of the forearm. That bedding looks nice, freefloats and centers the barrel, and appears stong enough having withstood a first shooting session of 15 shots. The scope is rock solid in the Ruger extended mounts and has not moved. The front-bell of the compact scope clears the end of the receiver by about 1/16". There are no apparent problems with the scope.)

Also, while there was a varying breeze (0-10mph?), the groups were 2" up to 4" in their vertical component. Another 'squeezing trigger on safety' surprise "test" suggests that this is not primarily shooter induced. Some 338 groups on the same day were sub-MOA in a known rifle, though with some groups over-MOA and a distinctly horizontal orientation (probably wind influenced--I concentrate on a target, not on the wind).

So a question for me becomes--

is anyone in North America going to have their reamer modified to a short throat?

Will the short throat reamer be available to McGowen barrels?

With the results being what they are on bands bullets

I am likely to shorten my reamer pending results of testing. I am not likely to go less than .5" though as I don't believe one caliber makes any difference over 1/2 caliber for accuracy but is worlds difference in pressure.

quote:

Originally posted by jeffeosso:
With the results being what they are on bands bullets

I am likely to shorten my reamer pending results of testing. I am not likely to go less than .5" though as I don't believe one caliber makes any difference over 1/2 caliber for accuracy but is worlds difference in pressure.

Yes, 1/2" would provide a wider pressure window for loads and pontentially higher velocities.

However, on a practical side, has anyone even reached a max pressure yet on the 500 AccRel? I chose the 500 AccRel because I thought a 7000 ftlb cartridge was sufficient and didn't plan to use an 8000+ ftlb 500 Mbogo. I would expect that even a short 0.25" will go up to 7300 ftlb.

Can quickLoad verfiy this?

416Tanzan,
QuickLoad makes no allowances for throat in its simulations.
As long as you have 0.050" of "jump"/free-travel of bullet before hitting the lands, you are golden.
QuickLoad would not trifle with the minor pressure let-off of excessive free bore,
not wanting to encourage any false security free-riding to get lower pressures.

jeffeosso is just dragging his feet on the reamer alteration (shortening of free bore)
to save face for making such a lousy choice on the stupid throating.

No further testing of significance is going to be done unless he does it.
We already know what the throat spec should be:

1/2 bore to full bore length of P-S free bore.
Average that for best compromise on accuracy and pressure: 0.375" length of P-S free bore.

Throat longer, to maximum of .500" P-S freebore length,
only if you want to be able to shoot the milsurps and 50 BMG Hornady A-Max and such.
That is what I did with the 500 Mbogo.
Throat-wise it is best with the 640-750-grainers loaded long.
Good enough with the short and light hunting bullets, 450-600-grainers.
I like 1:10" twist barrels for the .510-caliber.
1:12" twist is great for .500-caliber, since long and slow milsurps do not apply there.


Interesting that the TSX bullets have gotten so sloppy small.

The .511" diameter free bore should be the maximum diameter when you consider bullets are going to be .508" to .510".

My 49-10 throat of .252" length and .502" diameter is looking better all the time,
especially with consistent bullets of .500" diameter.
Glad I did that.
0.501" diameter, cast-lead, gas-checked, pistol bullets at low velocity for plinking and "small game" are also easy.

Contact Gina at www.gscustomusa.com for FN bullets. They are now producing small numbers of product and any catalog item can be ordered from her. Contact me on gerard@gscustom.co.za for tech data, should it be needed. HV and SP bullets will be made in the US within the next four to five weeks.

Gerard,

I think 416Tanzan is going to be wanting to get some of your HV bullets if he ever gets a shorter throat on his 500 AccRel.
I see the G1 BC for that bullet is: .328 @ 2600 fps, .332 @ 2100 fps
http://www.gsgroup.co.za/510450HV111.html


Is there a picture anywhere of the redesigned .510/450-grain HV?
What is different now? Nose cavity?
Here is the old one that kills cape buffalo like lightning, at 2654 fps MV, whether they expand or not:

2835 fps MV into dirt berm at 50 yards:



2654 fps MV into cape buffalo shoulder bones and heart at 80 yards (nose pinched/bent), killed buffalo, tumbled through heart;
and second one opened on chest shot insurance payment at 10 yards, same MV:











Also it says .510" for .512"groove/.500"bore such as 500 Jeffery and 500 NE.
Is the 450-grainbullet truly .510" on the drive band diameter now?
The heavier 50BMG HVs are .510" diameter for .509" groove?

Post a picture, please, and I'll order some more of the new ones if I like what I see.

There should be a rash of shorter throated 500 AccRels soon, and that rifle is certainly capable of 2654 fps with a 450-grain/.510-caliber HV.
First one I ever used on buffalo was a killer:

Tanz,, Ulrik, and everyone else with a 500 AccRel
I apologize, as I did when then started, as no one has ever seen these types of results before. Not a single person on the planet has seen banded copper/brass bullets stripping off the body in a .510 bullet -- I am still stunned that this is reality - and even though the bullet performed perfectly well on the game, it needs to be resolved -

I can always grind off more, if I have to, from my original reamer - which is sitting about 3 feet from me -- I am tempted to start at .75, but I will start at .510 -- i think have some solids in both of bullets we are seeing the issue with, and I have a barrel i can test, then setback and retest with ....

would be nice to actually see the results -

I don't think less than .510 improves anything -- but I didn't think the longer throat would matter, either --

As I am in the process of selling my house and moving my shop, and 3/4 of my stuff is packed up .....

Jeffeoso,

Your apology is appreciated and I also recognize that everything was done in good faith.

As for long freebore and accuracy, I only have the observations of others in an old article that I dug up. They simply said that deterioration into noticeably lower accuracy tended to start after 2-bore and became even more common after 3-bore throated barrels. Most of those observations were presumably done on lighter calibre hunting rifles (270-300) so there is also a question of how that will transfer to larger calibre, where bullets become relatively shorter or the sectional density increases with the same shape because of the different mathematical functions of diameter-squared vs volume-cubed.

I have not seen this picture before. An FN when you need it and an HV when you want it.

quote:

Originally posted by Gerard:
I have not seen this picture before. An FN when you need it and an HV when you want it.

Gerard,
Well it certainly worked that way, that time.
Thank goodness!
Please go to the "GSC Bullets: Made In USA" thread

http://forums.accuratereloadin...4711043/m/3671061871

to continue discussion on latest design of the .510/450-grain HV bullet,
which should be excellent in a sanely throated 500AccRel.
I like it greatly in the 500 Mbogo.

for me it was the default bullet for deciding on a 500 AccR. The AccR should be able to match the 2650 fps of your hunting load, so it would have been good to go.

quote:

Well it certainly worked that way, that time.

It did what it was designed to do, be an FN when it should be and an HV when it should be.

quote:

Originally posted by jeffeosso:
Tanz,, Ulrik, and everyone else with a 500 AccRel
I apologize, as I did when then started, as no one has ever seen these types of results before. Not a single person on the planet has seen banded copper/brass bullets stripping off the body in a .510 bullet -- I am still stunned that this is reality - and even though the bullet performed perfectly well on the game, it needs to be resolved -

I can always grind off more, if I have to, from my original reamer - which is sitting about 3 feet from me -- I am tempted to start at .75, but I will start at .510 -- i think have some solids in both of bullets we are seeing the issue with, and I have a barrel i can test, then setback and retest with ....

would be nice to actually see the results -

I don't think less than .510 improves anything -- but I didn't think the longer throat would matter, either --

As I am in the process of selling my house and moving my shop, and 3/4 of my stuff is packed up .....

jeffe,
No need to appologize. You did what you thought would work best.

When you get the reamer modified let everyone know where you will send it. I'll send in my rifle for a rebarrel. I vote 0.500", or the shortest allowable with milsurp. I"ve never shot any bullets out of mine over 2100fps and never will so I'm not so concerned with max pressure loads.

By eyeball alone you can tell that parallel-sided freebore length requirement is quite short,
unless you seat very long with the Hornady 750-grain A-Max or drive-banded bullets,
some of which are not even 50 BMG bullets.
In fact, you cannot seat the milsurps out very far at all, or you will have nothing but a boattail in the case:

Pretty pictures.

It looks like the mil-ball needs about a calibre of freebore, and 0.25" would be too short for shooting some, but not all of those funny, long, non-hunting bullets.

But none of them interest me. I am building the rifle so that I can carry the safest weapon that I can when walking after Nyati, and that includes without a PH friend along. I have been very impressed with the sub-MOA accuracy that RIP produced with the 49-10 and basically, that is my target with the 500 AccR.

So I would still like to get a freebore of 0.25". Even that is on the long side of normal for bullets that are 'bore-riding' on the nose. If a bullet is a bore-rider after a seating groove and front sealing band there will probably be about 0.20" inch of jump to the start of the leade. that sounds plenty long to me.

Yes, it's a big bore but we still want accuracy and the pressures should still be 60K or less for any loads up to around 7000 ftlbs. I'm still trying to get my longthroat loads up to 7000 ftlbs. Probably next time out. The long freebore just keeps pressure and velocity relatively low.

If there are different "short throats", will that undermine the general acceptance of the cartridge?

should a short short throat of 0.25" have a different name like "500 Accurate Nyati?

Probably just keep 500 AccRel and ignore the throat except in reloading recipes.

"500 Accurate Reloading And Accurate Shooting"
"500 Tanzan Accurate Reloading"
"500 TARZAN"

quote:

Originally posted by 416Tanzan:
I would still like to get a freebore of 0.25". Even that is on the long side of normal for bullets that are 'bore-riding' on the nose. If a bullet is a bore-rider after a seating groove and front sealing band there will probably be about 0.20" inch of jump to the start of the leade. that sounds plenty long to me.

Yes, it's a big bore but we still want accuracy and the pressures should still be 60K or less for any loads up to around 7000 ftlbs. I'm still trying to get my longthroat loads up to 7000 ftlbs. Probably next time out. The long freebore just keeps pressure and velocity relatively low.

Agree...
I have struggled to get pressures up and reach the vel I wanted, and QL was FAR away whith its prdictions.. (QL stating much higher vel and pressure with a given load)... RIP demonstrated clearly that .25" freebore is sufficuient (we also know that from many other calibers), well perfect actually. He get good velocities and accuracy. Same can be expected in the very very similar 500 AccRel ST.

Jeffe,
It is very difficult to design a cartridge that successfully bridges the use of the long/heavy milsurp 50 BMG bullets, modern bore-riding monometal hunting bullets, and everything in between. Unfortunately the original P-S Freebore specification of the 500 AccRel missed the mark at high velocity with the modern bore-riding monometal hunting bullets which was an unknown issue when the specification was set 5-years ago. I don't believe you need to apologize for your efforts.

Jeffe, Buffalo, ptaylor, Tanzan, et al..
Perhaps the simplest solution is 2 new reamer specifications for the P-S Freebore for the 500 AccRel… While it may sound dumb at first why not go with this:
Original 1.25” P-S Freebore = 500 AccRel LT (Long Throat)
New 0.510” P-S Freebore = 500 AccRel
New 0.250” P-S Freebore = 500 AccRel ST
Yes it is unwieldy for now but in the future likely few future chamberings will done with the 1.25” P-S Freebore with the two new specifications – the .0510” which accommodates milsurp bullet use and hunting bullets while the 0.250” is optimized for bore-riding monometal hunting bullets sans milsurp bullet use.

Just update the data contained on AmmoGuide Interactive to show the three P-S Freebore specifications and just reference that with the loading information.