What action, larger bolt face?

The 500 AR uses a Rigby diameter bolt face. Two actions that have proven to work are the Ruger M77 (3.4" magazine) and Winchester M70 (3.6" magazine). Guess I should note that a M98 Mauser action would also work, just a bit more expensive to get it completely ready.

Issues are 2-rounds in the magazine unless using a Rigby style drop floorplate (M77 and M70) or an extended style magazine (M70). I believe the 500 AR uses shortened and reformed 416/450 Rigby brass (or Hornady 416 Rigby cylindrical brass) so extractor would be modified for that groove size.

Almost forgot, there are two reamer specifications; the original 500 AR with a 1.250" free bore and the 500 AR Nyati with a 0.252" free bore. The original works fine with C&C and copper monometals - the Nyati was developed for use with brass monometals. Both will handle long 50BMG bullets single loaded only.

I have a .500/338 Lapua Magnum (very slight difference in case dimensions and .500 caliber vs .510 caliber of the 500 AR) on a FN commercial M98 Mauser action using Wiebe 4MJ (standard depth 4-down 404 Jeffery) bottom metal. Very minor fitting of the cartridge (shoulder, neck and bullet diameters) to the walls of the magazine and it holds 3-down with room to fit the 4th round to slip under the extractor. Obviously slightly different extractor groove size and rim depth with the 338 LM brass than with 416 Rigby brass.

Hope this helps.

Quality cartridge produces headstamped 500 Acc Rel brass.

I am not sure what its groove dimensions are and I am not around the rifle at the moment for any checking. Perhaps someone else could measure the extractor groove?

On accuracy with the 1.25" freebore, I am not sure that such a long freebore has been shown to be reliably accurate even with copper at various velocities.

I was not able to get good accuracy in my first outing with the long-throated version on a Hogue rubber-plastic stock. However, I subsequently determined that free-floating the barrel on top of a forearm secondary recoil lug did not seem to allow good accuracy with either the short freebore, .252", or a laminate wood stock. Only by creating a forearm tip pressure point did I achieve good accuracy before again cracking the laminated stock. I've already cracked two Boyd's laminated stocks and plan to rectify all of this next Spring when I might get a chance to play with the rifle again.

What was definitely confirmed on the freebore was that the long 1.25" freebore was shearing the brass on brass bullets and sending out a .510" projectile at a reduced .500" diameter. Someone recovered a solid from an elephant skull and wondered how the skull was able to reduce the bullet to a round, relatively smooth .500". Pretty nifty trick. Of course, it was the lands that were doing the shearing, not the elephant skull. That is what led to the 0.25" freebore reamer and 500 Accurate Reloading Nyati version. Capoward has more information on this.

quote:

Quality cartridge produces headstamped 500 Acc Rel brass. I am not sure what its groove dimensions are and I am not around the rifle at the moment for any checking. Perhaps someone else could measure the extractor groove?

From what we've previously been informed, QC procures Hornady mfg 416 Rigby brass in cylinder form; the groove dimension should be according to CIP specification.

quote:

On accuracy with the 1.25" freebore, I am not sure that such a long freebore has been shown to be reliably accurate even with copper at various velocities.

The original 500 AR freebore specification was in use within the USA and Australia for a number of years prior to the development of the current banded brass monometal bullets. Comments provided by the long term users indicate MOA accuracy using both traditional hunting bullets and with the longer 50 BMG target bullets.

Newer testing indicated no band abrading with copper banded monometal bullets - only with brass banded monometals.

quote:

Originally posted by 416Tanzan:
What was definitely confirmed on the freebore was that the long 1.25" freebore was shearing the brass on brass bullets and sending out a .510" projectile at a reduced .500" diameter. Someone recovered a solid from an elephant skull and wondered how the skull was able to reduce the bullet to a round, relatively smooth .500". Pretty nifty trick. Of course, it was the lands that were doing the shearing, not the elephant skull. That is what led to the 0.25" freebore reamer and 500 Accurate Reloading Nyati version. Capoward has more information on this.

It was not an ele scull ... I was a hippo lengthwise... I did the shooting..
Both copper AND brass monometals were sheared in the rifling to .500" diameter - only bullets which didnt was the DGS solids from Hornady (which were the only C&C bullets I tried in the 1,25" freebore original version..)..

quote:

Both copper AND brass monometals were sheared in the rifling to .500" diameter

Capo-
do you think that sheared bullets would do 1" at a 100 yards? Maybe we've discovered a new bore-riding technique??


Any accuracy tips or testing on the 500 AccRel are appreciated on my end.

quote:

Originally posted by 416Tanzan:

quote:

Both copper AND brass monometals were sheared in the rifling to .500" diameter

Capo-
do you think that sheared bullets would do 1" at a 100 yards? Maybe we've discovered a new bore-riding technique??


Any accuracy tips or testing on the 500 AccRel are appreciated on my end.

buffalo,

I stand corrected on the copper monometals.

Tanz,

Accuracy Tips...
1st - a well and correctly reinforced stock (or a stock with a full length bedding block).
2nd - keep the action screws correctly torqued.
3rd - bullet and powder combo that gives 100% powder burn a few % under 100% loading.
4th - ignore "target MV" and go with best accuracy. I know this one might not make sense but often the reloader goes for absolute maximum velocity when slightly lower velocity gave much tighter groupings.
5th - and perhaps the most important for us mortals is to keep your shoulder well padded when shooting from the bench.
6th - feel free to ignore any of the above...