I think that owners of 500 Accurate Reloading rifles may want to do something collectively if desiring to hunt with something other than a 570TSX or a softlead softnose.


In light of the lack of 500AccR to shoot brass bullets with a 1.25" freebore, what should owners of 500AccRel's do? How should they prepare hunting loads?



1. Several 500AccR affecianados to band together and have a copper CEB MTH bullet set up and run off at about 430-450 grains.

This should be functionally similar to the GSCustom 450 grn HV. Costs for the CEB would probably be less, and access in NorthAmerica would be easier than the SouthAfrican GSC. RIP's experience with the 49 calibre is promising, indeed, and I could be tempted to forgo a rebarreling if I my rifle would shoot such CEB's the way RIP's does. The nose should ideally be kept to 0.70" in order to feed in standard magazines. The biggest downside on this is that accuracy for such a bullet in a 1.25" freebore is an unknown. Back in the days when freeboring was a more common calibre enhancement tool it was considered risky when people went over 2 calibre freebore. Sometimes it worked, sometimes not.
However, organizing such a bullet run can also be used in tandem with the next option.

2.
A Reamer could be adjusted that could be deposited with someone like McGowen Barrels.

Are there any 500AccR reamer-owners out there who would consider this?

I would recommend a 0.25" freebore. I've been told that Manson Reamers will do such a modification fairly inexpensively and quickly. Maybe Buffalo has something to say about this. Maybe even McGowen Barrels could do the reamer adjustment if Jeffeoso was on board with it. This is out of my erpertise.


This has been posted on the thread
"500 AccRel throat, reamers, and freebore", too.
One or the other should be used.

I'm interested. I say lets try the CEB bullet idea and see if they shoot. If not lets get a new reamer made. Whats the shortest freebore you could have and still shoot APIT bullets?

i wouldn't suggest anything less than .510 .. gentlemen, we are at the edge of the unknown.. frankly, i don't believe, for one second, that the long throat is striping the engraving out of the bullet..

i am happy to see what the test results will show .. i will go on record for saying i don't believe this to be an issue.. but i will also eat crow the second we find out otherwise...

the round is designed to allow for the (once) cheap milsurp bullets to be used as plinkers, and no one ever reported the CHIPS (chips, chunks, turnings) of the brass left in the throat.

I am not upset for the test, though this post may come over like that

I do intend for a .510 throat on the 49 caliber AccRel,a .498 groove.. but that's because there's no milsurps to shoot.


we have this exceptional case on these EXCEPTIONALLY AWESOME bullets, with huge penetration on the bullets..

feet of penetration with "stripped" bullets.. pretty darn cool, in fact

however, if we do decide to shorten the neck (which isn't hard) i will be removing all references to the milsurp bullets, as they would not be even close to safe in a short throat gun

quote:

Originally posted by 416Tanzan:
,,, Back in the days when freeboring was a more common calibre enhancement tool it was considered risky when people went over 2 calibre freebore. Sometimes it worked, sometimes not.

what does that mean, as i don't understand ...

paradox rifles had FEET of freebore, so i don't get the risky part...

The risky part was potentially ruining the usefulness of a barrel and needing to order a re-barreling.

People would report a drop in accuracy at some stage of progressively extending freebore and testing, but that once accuracy dropped off, it was too late to fix that barrel. Once freebore is cut into a barrel one cannot go back to less freebore.

I thought that was it.. but annie oakly used a smooth bore rifle.. 100" freebore..


I never read of a risk on long throated guns for stripping bullets, which is what I thought we were talking about..

accuracy? gents, the 500 ar tends to be as accurate as any bigbore.. except with cast bullets, which are short, in fast twist barrels, which is never an accurate combination.. ever..


I think we are taking a single bullet combo and calling it fouled..

but we can set the barrel back .750 and recut the chamber, IF buffalo's tests show improvements...

I asked McGowen about setting the barrel back.

John, the one who handled my barrel, thought that the CZ contour was already close to minimum for the size of cartridge and he recommended against any thought of setting things back .75" inch. My 22" barrel has plenty of length, the problem is meat around the breach end.

1.250" of parallel-sided freebore, plus leade, is a lot of throat!
Nicely tight at only .511" diameter,
but still too long.

The old 2-caliber-free-bore .375 Wby is dismal for accuracy and velocity compared to the new 1-caliber chamber.
I have both and have compared them.

Consider the CIP chamber for the 50 BMG if anyone is worried about using milsurp bullets in a 50-bore.

The actual parallel-sided freebore length of the 50 BMG is only 0.2579" long,
but leading up to that is a 15-degree per side run of .0823" length, the chamfer/step-down from case mouth to freebore.

This is different from the usual 45-degree chamfer or step-down from chamber neck to throat that is seen in most cartridges.

This is news to me, never looked at that before.

The total length from neck-2 or "collar-2" at case mouth to the end of the parallel-sided free bore is thus:
0.2579" + 0.0823" = 0.3402"

But that parallel-sided free bore diameter is 0.5181", for a bullet diameter of .510".

At the end of that short and wide parallel-sided free bore, the leade is a very gradual 0-degree-34'-59" taper over a run of .9665".

At the end of that leade the diameter is down to bore diameter of 0.4984" minimum or .500" nominal.

Total throat for the 50 BMG:

(In this special case we need to add in that case mouth chamfer length since it is so long and gradual, and not the usual 45-degree step-down to free bore.)

.0823" + .2579" + .9665" (leade) = 1.3067"

That is a lot of built in slop for combat machine gun use in an M2.

Accuracy chambers for snipers and sporters???

I started shooting milsurps in a 500A2 in 1999.
Caliber-length freebore up to leade is more than enough to get all you want out of any milsurp.

The .510-calber 500 Mbogo used caliber-length and .511" diiameter for the parallel-sided free bore.

The .500-caliber 12.7X68 49-10 used half-caliber-length and .502" diameter for the parallel-sided free bore.

I like both, the former for milsurps and long civilian target bullets,
but the latter is better for the stubbier sporting bullets.

Both can be supremely accurate with the right bullets.

45-degree step-down from case mouth to free bore, and 1.5-degree leade angle is pretty standard, good for the .500 and .510 rifles.

A separate throating reamer can be used to lengthen a short-throated chamber, by a competent gunsmith.

Rip. interesting read. Btw the throat isn't relevant to our discussion, as the BMg has case capacity at nominal length. Using milsurps at vastly past nominal is what drives the throat.

Thanks for the explanation on your thinking

Wrong, jeffeosso:
There is only so far out that you can practically load a milsurp, and caliber-length freebore will do it.
You have to have some parallel-sided bullet shank inside the case, besides the boat tail hanging down in the powder.
Most of those 50 BMG bullets do not have a very long run of parallel-sided bullet shank.
Most are long-ogived nose and long boat tail.
Even for the longest bullet I could come up with in the 500A2, 0.587" of parallel-sided free bore was more than enough.

Anyway:
Milsurp capabilities should be a secondary consideration for use in a practical sport hunting rifle.
The misguided idea that you need 1.250" of parallel-sided freebore should not dictate the throat on such a rifle.
You cannot even make good use of half that amount of free bore.

Please show a dummy round that requires that much free bore.

Go here: http://forums.accuratereloadin...043/m/3061083571/p/2

quote:

Originally posted by ptaylor:
I'm interested. I say lets try the CEB bullet idea and see if they shoot. If not lets get a new reamer made. Whats the shortest freebore you could have and still shoot APIT bullets?

PTaylor-- so far it's only two of us with a declared interest, but that may change as we get towards a final design.

some guidelines on the design:
1. We don't need over 500 grains since that is already covered by Woodleigh, Barnes, and Hornady at reasonable prices.
2. We want an all-purpose, flat-shooting, copper bullet with a decent BC.
3.BC goes down as the weight goes down, so we may want to aim at about 450 grains and not under 400.
4. Monometal and guaranteed penetration are a must because these would be taken to Africa.
5. Is there a way to test before production to insure that there is no stability issue like with the similar weight Raptors?



I propose:
400-450 grains as the target design range.
It might as well be designed for a sharp tip from the beginning. It doesn't need a 13º HP bevel. It can be free to find its own best profile.
0.7" nose would guarantee feeding in a normal magazine. 2.65" + .7 = 3.35"
BT or beveled flatbase is all the same to me, it's first a question of overall bullet length and stability for the weight. (Actually, there shouldn't be any stability problem at this diameter. I still don't understand the Raptor thing.)


But I do not have design tools or time to work on this, so proposals are welcomed.

Tan...ptaylor,

Having worked with Dan to create my two CEB MTH bullets in .423 and .500 calibers I would recommend that you collaborate with the following parameters - sorry these are in the 'see spot run' methodology but hopefully it will eliminate many questions further in the process...:
1) Bullet construction - Copper for this bullet
2) Unseated bullet length - I recommend you take your shortest internal magazine length, deduct your spec case length of 2.65", then deduct 0.040" for plenty of wiggle room and that's your target unseated bullet length...
3) Seated bullet length - figure the 'maximum' seating depth you're wiling to go with, that's your seated bullet length.
4) Overall bullet length - add your seated and unseated bullet length and that's your maximum overall bullet length...
5) Bullet shape styles- HP Spitzer nose... Base? Radius edge Flat Base or Boat Tail? Your call but I recommend you determine the typical maximum range you'll be shooting the bullet then adjust your hold for the atypical shot. If typically within 350yds go with the Radiused edge Flat Base... If typically further than 375yds go with the boat tail base...
6) Be willing to slightly adjust #3 and therefore #4 based upon your decision on #5...
7) Driving bands or no driving bands - The CEB MTH bullet style typically on has the single STB (Seal Tite Band) while the FBH bullet has the STB plus a number of very narrow driving bands. My two bullet styles are a hybrid style; overall MTH shape with the additional FBH narrow driving bands...the combined amount of driving band material to be displaced on my two bullets is less than the total banding material of the BBW#13 bullets in each caliber...
8) Ballistic Coefficient - Just tell Dan to shape the bullet within your selected parameters to maximize the BC; you'll be extremely happy with what he delivers...
9) Total bullet weight - Let final bullet weight fall where it falls after you've satisfied your criteria in #'s 1-8...

Again, sorry for the 'see spot run' of this post but as you get into your design you'll find that your target bullet weight is almost the least important design aspect that you're interested in...

RIP came on board with me on the 430gr .500 caliber MTH bullets so we split the bullet run. I did a full 300 bullet run on my own in the .423 caliber. I recommend you guys split a 300 bullet run which is just about a full rod length of material though they'll be maybe 10 bullets maximum left over for Dan to send a few to Michael for bullet box testing...

Good luck!...whatever you decide to do...

quote:

Originally posted by capoward:
Tan...ptaylor,

Having worked with Dan to create my two CEB MTH bullets in .423 and .500 calibers I would recommend that you collaborate with the following parameters - sorry these are in the 'see spot run' methodology but hopefully it will eliminate many questions further in the process...:
1) Bullet construction - Copper for this bullet
2) Unseated bullet length - I recommend you take your shortest internal magazine length, deduct your spec case length of 2.65", then deduct 0.040" for plenty of wiggle room and that's your target unseated bullet length...
3) Seated bullet length - figure the 'maximum' seating depth you're wiling to go with, that's your seated bullet length.
4) Overall bullet length - add your seated and unseated bullet length and that's your maximum overall bullet length...
5) Bullet shape styles- HP Spitzer nose... Base? Radius edge Flat Base or Boat Tail? Your call but I recommend you determine the typical maximum range you'll be shooting the bullet then adjust your hold for the atypical shot. If typically within 350yds go with the Radiused edge Flat Base... If typically further than 375yds go with the boat tail base...
6) Be willing to slightly adjust #3 and therefore #4 based upon your decision on #5...
7) Driving bands or no driving bands - The CEB MTH bullet style typically on has the single STB (Seal Tite Band) while the FBH bullet has the STB plus a number of very narrow driving bands. My two bullet styles are a hybrid style; overall MTH shape with the additional FBH narrow driving bands...the combined amount of driving band material to be displaced on my two bullets is less than the total banding material of the BBW#13 bullets in each caliber...
8) Ballistic Coefficient - Just tell Dan to shape the bullet within your selected parameters to maximize the BC; you'll be extremely happy with what he delivers...
9) Total bullet weight - Let final bullet weight fall where it falls after you've satisfied your criteria in #'s 1-8...

Again, sorry for the 'see spot run' of this post but as you get into your design you'll find that your target bullet weight is almost the least important design aspect that you're interested in...

RIP came on board with me on the 430gr .500 caliber MTH bullets so we split the bullet run. I did a full 300 bullet run on my own in the .423 caliber. I recommend you guys split a 300 bullet run which is just about a full rod length of material though they'll be maybe 10 bullets maximum left over for Dan to send a few to Michael for bullet box testing...

Good luck!...whatever you decide to do...

Thanks, Capo, that is helpful for getting started.

Most is clear except evaluating the driving band thing. One thought: although these will first be tested in long throats, it is possible that some of us will rebarrel and end up using in a short throat. Driving bands are probably more useful in a short throat in my uneducated view.

Another point of interest, what is the ballpark of what 300 bullets will cost? Do you have an idea of how many are needed before the next price break?

I looked at "Thor Bullets" are saw a very pretty 50cal with a sharp pointy blue tip. I wonder if that kind of tip could be available for this design?

Tan,

The 500/338 Lapua Magnum (12.7x68 Magnum, 49-10) chamber is cut for clearance of the bullet seated case neck with the bullet computed at full caliber diameter. The typical MTH bullet behind the STB is a slick bore-ridding shank at slightly under bore diameter; there is a short caliber diameter band section in front of the STB which keeps the bullet centered as it passes through the free-bore section into the fully grooved barrel. The typical FBH bullet is slightly under bore diameter in front of the STB with multiple-narrow caliber diameter driving bands behind the STB to the radiused base band. So I had Dan add the narrow FBH banding to the shank area behind the STB to maintain the proper case neck tension and overall chamber to case neck design diameter clearance. As an FYI the STB is typically 0.001" larger than caliber diameter as a pressure seal.

The typical 3+1 BBW#13 banding has 0.200" gross banding material that is displaced on the .500 caliber bullet. Off the top of my head I believe we were at about 0.180" gross banding material to be displaced on my MTH bullets which included the short groove diameter band fronting the STB, the STB, and the narrow FBH shank bands. So pretty much a win-win situation.

Cost is totally dependent upon the price for the copper rods - brass rods would have much cheaper... Contact Dan through the CEB website and he can give you current price estimates...

Tips??? I don't know, Dan is now doing tips for the BBW#13s and ESP Raptors so perhaps he would be willing to look at doing tips on your .510s...maybe use a rat caliber tip with matching HP diameter. But I wouldn't worry as the HP on my .500s work just fine; the low velocity expansion point is somewhere past 900yds...

Hope this helps...

quote:

Tips??? I don't know, Dan is now doing tips for the BBW#13s and ESP Raptors so perhaps he would be willing to look at doing tips on your .510s...maybe use a rat caliber tip with matching HP diameter. But I wouldn't worry as the HP on my .500s work just fine; the low velocity expansion point is somewhere past 900yds...

All very helpful.

On tips, I like tips for the BC.
Since I intend to hunt at 2600fps, I don't worry about low velocity expansion too much.

No sane rationale has been offerred for such a throat: 1.250" parallel-sided free bore plus leade.

No bullet or cartridge will perform up to its potential in such an insane throat.

Cut your losses.
Quit wasting your time.
Get a new barrel and apply some sanity to the throating.
Be happy.

quote:

Originally posted by ptaylor:
I'm interested. I say lets try the CEB bullet idea and see if they shoot. If not lets get a new reamer made. Whats the shortest freebore you could have and still shoot APIT bullets?

Notice that the blacktip-AP milsurps need less than caliber-length freebore, shown here in 500 A-Square.
It is crimped on the existing cannelure, but could be loaded longer, with no crimp,
and there is lots of room for that with a caliber-length parallel-sided freebore.
Read the ruler.
Guess what? That Hornady A-Max is loaded out about as far as possible,
and yep, you guessed it,
caliber-length, parallel-sided free bore is more than enough for that too:

If I cant say nothing nice I should just shut up right

Let's wait for anders and Ulrik's testing please before we jump off into another throat please

Ron - Appreciate you most of the time. So you built a 500 ar or you will if the throat changes? Just trying to understand your passion in this and where you are coming from.

quote:

Originally posted by jeffeosso:
If I cant say nothing nice I should just shut up right

Let's wait for anders and Ulrik's testing please before we jump off into another throat please

Ron - Appreciate you most of the time. So you built a 500 ar or you will if the throat changes? Just trying to understand your passion in this and where you are coming from.

Freedom of speech, jeffeosso.
The exchange of ideas.
Just trying to bring enlightenment.
A throat with 1.250" of parallel-sided free bore is one that only Bozo could love.

I see you cannot defend it, hence your inability to say anything nice, eh?


Why keep it?
I have plenty of "fifties" don't need another.
I have shot plenty of milsurp in 500 A2, and when I was first starting out I lengthened the throat on the first 500 A2,
then had my own reamer made from dummies sent to Dave Manson.
Shoulder came out on that at 30 degrees (instead of 35 degrees on 500A2) and I specified a freebore length of .587", called it the .510 JAB.
That was longer throated than needed for milsurps, but it worked well.
If I did it again, I would stick to .500" free bore length,
just like on the 500 Mbogo.
Got two of those also.
Not needing to use Milsurps in the 12.7X68 49-10, that free bore length came out at .252".
It worked wonders.
Now there are more bullet choices in .500 than in .510.
I am happy.

IIRC, Ulrik and Anders were proposing getting a new barrel and using a more extremely tight throat than I would recommend for general purpose.
I do not see how waiting for further tests by them will be helpful.
They are the ones that brought the stripped brass bullets by long throat to our attention.
They chose the proper route of new barrel and shorter throat.

quote:

Originally posted by jeffeosso:
...

Let's wait for anders and Ulrik's testing please before we jump off into another throat please

...

and

quote:

Originally posted by RIP:

...
Ulrik and Anders were proposing getting a new barrel and using a more extremely tight throat than I would recommend for general purpose.
I do not see how waiting for further tests by them will be helpful.
They are the ones that brought the stripped brass bullets by long throat to our attention.
...

Ulrik and Anders are not planning to test the long throat further, they will be working from a short throat version. So I don't see how their testing will help the long throat question.

In about three weeks I hope to test some TSX 570 for accuracy in a long throat on a Hogue stock. I might get a chance to compare some brass 570 CEB's.

Will 100 yards be enough to show distinctive accuracy differences? I will also have access to a 200 yard range.

Iirc anders plans in tight nil throat reamer and a throater to play with throat length.

Yep. I do recall correctly.

quote:

Originally posted by hatting:
opdate:

have ordert a uni throat reamer in .510/.5102
and a lothar walther barrel twist 1/10
will send the 500 acc-rel reamer bag to mansonreamers and have the throat removed

then ulrik and I vil make som test with the throat from near zero to 1,25" then ulrik and I vil make som test with the throat from near zero to 1,25"

and get some pressuregauges on the barrel to se what vil happen

best regards
Hatting

Unless their plans changed I am content to wait

I haven't followed this much but why don't you get Dan to make you a bullet with a band at the nose of the bullet? This might help with those guns with the long free bore. If you would like I could make a couple of sample bullets for you to try before you get Dan to make a run. PM me and tell me what you want and I'll see if I can help.

Sam

quote:

Originally posted by srose:
I haven't followed this much but why don't you get Dan to make you a bullet with a band at the nose of the bullet? This might help with those guns with the long free bore. If you would like I could make a couple of sample bullets for you to try before you get Dan to make a run. PM me and tell me what you want and I'll see if I can help.

Sam

Sam,

The easiest solution without a rebarrel with a shorter free-bore would be BBW#13 Solids and HP NonCons cut from copper...as the copper seems to engage the rifling without abrading the driving bands.

Jim,

If copper will work then yes that is the way to go. I just thought a band near the nose would get rid of all the free bore.

Sam

quote:

Originally posted by jeffeosso:
Iirc anders plans in tight nil throat reamer and a throater to play with throat length.

Yep. I do recall correctly.

quote:

Originally posted by hatting:
opdate:

have ordert a uni throat reamer in .510/.5102
and a lothar walther barrel twist 1/10
will send the 500 acc-rel reamer bag to mansonreamers and have the throat removed

then ulrik and I vil make som test with the throat from near zero to 1,25" then ulrik and I vil make som test with the throat from near zero to 1,25"

and get some pressuregauges on the barrel to se what vil happen

best regards
Hatting

Unless their plans changed I am content to wait

jeffeosso:
Why did you delete the original post date above?

So they are going to destroy a second barrel and see where it goes bad somewhere between zero and 1.250" of freebore?
Then properly chamber a third barrel and good to go?

And do it with brass CEB bullets, then if those work, anything else will work?

I suspect they have reconsidered this foolishness.
Wish they would post again about this.
We are waiting anxiously for them to confirm what we already know.


0.5100"-0.5102" is not a free bore.
It is a smoothbore,
Ludicrous itself for a sporting big bore,
unless they are planning to stick with maximum bullet diameter of .509" like Barnes TSX,
then it would be a limited utility custom throat.
PLUS 0.0006" to plus 0.0010" is the usual free bore diameter on the smaller-caliber sporting rifle chambers.
Not PLUS 0.0000"-0.0002".
Above: regarding parallel-sided free bore diameter.

Nothing wrong with the 0.5110" diameter for free bore of a .510-calber rifle.
0.5120" diameter would suit me fine too.
PLUS 0.0020" works great on a .500-caliber rifle, of mine, both of them.
But that free bore length is 0.252", an inch shorter than the bozo throat:
Cast bullet capable and 0.3 MOA capable with CEB brass bullets.
Remember that the CIP standard 50 BMG short and wide free bore is PLUS 0.0080" in diameter over bullet diameter.

Sam,
Put a band on the nose of the brass bullet: Still has to jump an inch to engage,
will probably shear that off too.
And 416Tanzan is not going to get the BC he wants with a caliber-diameter donut near the tip of the bullet.

Ok…joining today’s discussion. And again, I’m sorry for the long post again…

1st off I have no intension, at least for the foreseeable future, of building a 500 AccRell as my .500/338 Lapua Magnum aka: 12.7x68 Magnum, aka: 49-10 is under construction. So now that we know that I’m just taking up space in this thread, here I go…

Ulrik has a problem with his 500 AccRel when firing the brass construction .510 caliber CEB BBW#13 bullet as the brass banding is abraded to bore size without indication that the rifling has engraved the banding; this happened at an indicated 2320fps MV. Copper bullets engrave the banding without indication of abrading. So the potential cause of his brass bullet banding abrading problem with the brass CEB bullets are: 1) an issue with the rifling and/or chamber of this particular rifle, or 2) the 1.250” free-bore of the 500 AccRel specification is just to long for the brass construction banding to engage the rifling.

So although Ulrik and his gunsmith Hatting plan to test various free-bore length in an attempt to determine where the problem becomes a problem, perhaps the following data will shed some light on the likely problem area.

A couple of things that we are currently aware of are:
1st – That Michael is able to run the .500 caliber CEB BBW#13 brass construction bullets at up to 3000fps in his 500 MDM without the banding abrading issue that Ulrik and Hatting have encountered with the 500 AccRel. And,
2nd – That Michael has run his .510 caliber CEB BBW#13 brass construction bullets at 2323-2363fps MV in his .510 Wells Magnum without the banding abrading issue that Ulrik and Hatting have encountered with the 500 AccRel.

quote:

Originally posted by michael458:
In the 510 Wells I upped the charge from 95/RL 15 to 106/RL 15.....This gave a velocity boost of 232 fps with the 570 CEB BBW#13 Solid, and 256 fps with the 535 NonCon. With the 535 NonCon that gave us roughly around 10% more penetration with the bullet. It gave us about an inch more with some of the blades. Some blades went just past the 8 inch witness card with the higher velocity NonCon, and at low velocity none made it to the 8 inch witness card. A fairly substantial gain in penetration with the 570 #13 Solid, around 15% more penetration.

Regardless of gain, even at low velocity the penetration is fantastic and more than enough with both NonCon and Solid. This just points out--Once Again--That these noncons like velocity, as well as this nose profile solid. North Forks like velocity as well, but operate very fine at lower velocities too. It's the nature of proper designed bullets I IMO.





I have a good bit of work to do in the coming days, just trying to get to it all is the issue right now. I have planned some POI tests with the 535 NonCon and 570 Solid at 50 yds. I also want to do some terminals with the new 480 .457 Solid and 450 .457 NonCon, then some 50 yd POI tests with these as opposed to the 450 Solid and 420 NonCon in .458. An interesting POI test will be the 450 Solid and 450 NonCon. With the 450 NonCon being slightly longer than the solid. Same time I will want to do some pressure traces with the 480s and 450 NonCons in the 458 B&M. Then, we will take these same bullets to the 458 Lott for POI and Terminals, and see if we can push them a bit!

I want to stress the NonCons a bit as well. While a T'Rex is a bit too much stress on a NonCon, to expect petals/blades to pass that I do not. The remaining bullet will. I will do a T'Rex on the NonCons. What I think is a better test on the NonCons is to take 2 inches of test medium, and then some either 1 inch boards or even some 2X4 boards behind that and see what happens with the blades. The bullet will pass thru these, I have zero issues there, what I want to learn is what happens to the blades. While this can't simulate a buffalo or other animal, it can give us some more in depth information on how they might react in some circumstances.

This is the initial layout of work to come, I am sure while doing some of these we might come up with some new ideas to work on as well. Not sure how much I will get done the next couple of days, and I am going to have to make a run to get more test medium very soon, almost at the bottom of the pile now!

Michael

Above quotation pulled from page 119 of the Terminal Bullet Performance thread…

Ok…so now we’re narrowing the issue somewhat in the .510 caliber so we’re now more in a apples to apples comparison.

I also decided to dig though some of my storage boxes and pulled out my 2006 updated edition of Pacific Tool & Gauge’s The Gunsmiths Book Of Chamber Prints to run down some additional chamber data. So here goes:
Cartridge - Length of Freebore - Length from Neck Chamfer to Bore Diameter - Throat Angle
500 MDM = 0.375”- 0.6147” - 1º30’
500/338 Lapua Mag (12.7x68 Mag, 49-10) = 0.252” - 0.4958” - 1º30’
500 Jeffery = zero (not listed) - .4098” - 0º47’
50 BMG = 0.2579” - 1.3067” - 0º34’22 (Browning Machine Gun Barrel Specification)
50 BMG = 0.130” – 0.6251” - 1º8’45 (Frankford Arsenal Accuracy Barrel Specification)
50 BMG = 0.0817” – 0.6300” - 1º8’45 (Barrett Specification)
50 FCSA = 0.1338” – 0.5900” - 1º8’45 (S. Talbot Light Gun Minimum Specification)
510 Wells Magnum Express = 0.177” - 0.392” - 2º00’
510 DTC = 0.1303” - 0.4878” - 1º25’
500 AccRel = 1.250” - 1.4748” - 1º30’

So…looking at the above data I’d say RIP is in the proper range for the long/heavy BMG bullets with his 0.587” free-bore in his .510 JAB and is probably at the maximum for traditional hunting bullets with the 0.500” free-bore in his 500 A2

RIP has pictorially demonstrated more than sufficient free-bore to accommodate the longest commercially available BMG bullet with his 500A2 and referencing the 510 Wells and the 510 DTC I’d say that the free-bore range for the 500 AccRel MkII – designed specifically for hunting bullets – should be 0.1303” to 0.500” minimum/maximum range… I personally lean towards the middle and recommend a 0.252” to 0.375” minimum/maximum free-bore specification as working extremely well with the modern bore-riding monometal bullets while easily accommodating all current 570gr non-monometal hunting bullets. And for the throat – stay with 1º30’ as nothing tighter or looser is needed to maximize accuracy…

Ok, that’s my 2¢…

Oh yes…

quote:

Originally posted by srose:
Jim,

If copper will work then yes that is the way to go. I just thought a band near the nose would get rid of all the free bore.

Sam

Sam,

That would be a potential solution to the band abrading but it would only cut the free-bore down to approximately 0.750” but who knows if 0.750” is still too much free-bore… Also a band that close to the nose would definitely inhibit the penetration of the BBW#13 FN Solid bullet as previously identified by Michael with some of the early model .458 caliber bullets; I believe a =/>0.600” smooth nose length was identified as required to optimize FN Solid penetration.

OK I’m gone now until I finish my Saturday chores…

quote:

Originally posted by RIP:
No sane rationale has been offerred for such a throat: 1.250" parallel-sided free bore plus leade.

No bullet or cartridge will perform up to its potential in such an insane throat.

Cut your losses.
Quit wasting your time.
Get a new barrel and apply some sanity to the throating.
Be happy.

I ordered two new barrels, should arrive in August, two LW barrels with 1-10" twist. One we will do some experiments with, from zero freebore to the point where it starts stripping the bullets (CEB and Barnes solids). I am quite certain that my final barrel will end up with a 0,2- 0,25" freebore of .511" diameter (Hatting also ordered that diameter reamer) and that it will work perfectly...

quote:

Originally posted by buffalo:

quote:

Originally posted by RIP:
No sane rationale has been offerred for such a throat: 1.250" parallel-sided free bore plus leade.

No bullet or cartridge will perform up to its potential in such an insane throat.

Cut your losses.
Quit wasting your time.
Get a new barrel and apply some sanity to the throating.
Be happy.

I ordered two new barrels, should arrive in August, two LW barrels with 1-10" twist. One we will do some experiments with, from zero freebore to the point where it starts stripping the bullets (CEB and Barnes solids). I am quite certain that my final barrel will end up with a 0,2- 0,25" freebore of .511" diameter (Hatting also ordered that diameter reamer) and that it will work perfectly...

Good plan on throat specs for the 500 AccRel rebarrel.

A better plan than sacrifice for science on the other barrel:
You will have to sacrifice more than one more for statistical significance.
Forget about it.
We already know where things go bad: Somewhere past 0.587"
We do not need to know anymore precisely than that, because that is more than long enough for any practical use.

If Anders wants more work, useful work, not just busy work,
have him build another .510-caliber rifle,
like a matched pair of 500 AccRels.

500 A-Square?
500 Mbogo?
.510/.505 Gibbs?
500 Jeffery ... a real challenge for an energetic gunsmith, to prevent him from wasting a perfectly good LW barrel.

I have 500 Jeffery brass and dies and a bunch of 535-grain bullets that might work in a 500 Jeffery on a Wby Mark V straight stack.
That throat is all leade, no parallel-sided freebore.
See Jim's listing of throats above.
If I want to shoot milsurps in that, I would have Rusty McGee extend that throat to .500" length of freebore .511" in diameter.
That will have to wait until after he finishes the .375/404 JS of 2012 No.2 on an FN Mauser with Wiebe bottom metal.
Then a 400 Whelen on a Ruger Hawkeye.
I like rifles, pretty or ugly as long as they are accurate and functional.

Ulrik,

In this situation I agree with RIP, seems like a waste of a perfectly good (and not inexpensive) barrel to use it for the freebore testing unless you're going to recharger it to a much longer cartridge. I'd recommend selling the second barrel to someone who wants to build a short freebore 500 AccRel. But you are the individual paying the bill so it obviously is your choice.

If however you do continue with the testing perhaps you'd consider also testing some very long 50 BMG target bullets so that you'd also verify just how much freebore is needed to successfully shoot the military surplus bullets in the 500 AccRel. Just a thought...

thanks guys - will consider your suggestions...
Anyway Anders wrote to me this morning that he have asked David Manson to chenge the reamer to the following specs:

Cartridg: 500 AccRel
Length of freebore: 0.250”
Length from neckchamfer to Bore Diameter: 0.4748”
Throat Angle: 1º30’
Freebore Dia – 0,511

Dont you think that will work????

quote:

Originally posted by buffalo:
thanks guys - will consider your suggestions...
Anyway Anders wrote to me this morning that he have asked David Manson to chenge the reamer to the following specs:

Cartridg: 500 AccRel
Length of freebore: 0.250”
Length from neckchamfer to Bore Diameter: 0.4748”
Throat Angle: 1º30’
Freebore Dia – 0,511

Dont you think that will work????

You will not be disappointed with that decision. Just send Hatting a thank you...

i wouldn't go less than .510 .. i don't see ANY sense in going short short on this, all to make one, albeit exception, bullet work....

please, if you order through manson, have the ream marked 500 AccRel ST 0.25" for short throat

quote:

Originally posted by buffalo:
thanks guys - will consider your suggestions...
Anyway Anders wrote to me this morning that he have asked David Manson to chenge the reamer to the following specs:

Cartridg: 500 AccRel
Length of freebore: 0.250”
Length from neckchamfer to Bore Diameter: 0.4748”
Throat Angle: 1º30’
Freebore Dia – 0,511

Dont you think that will work????

Yes that is perfect.
The 500 Jeffery uses zero free bore, has only a leade of .511" diameter at it's widest and tapers down to .500"/bore diameter from there.

In such a perfect throat as you have selected, you will probably be able to use most all of the 50 BMG ball seated on the crimping cannelure.
Certainly all of the sporting bullets will work
with best potential accuracy.
Less powder needed to get to proper pressure and velocity.
More accurate.
Less recoil for velocity obtained too.
Straining a bit on that last one.