6.5CM both SA/bolt questions

[nimdabew]

Hi. I am trying to decide on what I want for my AR10 lower to be built at. I would like to make a 6.5CM AR10 for ammo commonality with my 6.5CM bolt gun that I want to build, but I am starting to second guess that strategy.

When I am going to load for my bolt gun, I am guessing that my COAL will be longer for the bolt gun just from the nature of having more space in the magazine, and if those don't fit in a Magpul AR10 mag, then I would have to load two different cartridges anyways.

Is there someone out there that loads for a bolt gun that can also use the same OAL so it fits in an AR10 magazine, but doesn't see that much reduction in their bolt gun usage? Is what I am a valid reason to want two different cartridges for my AR10 and bolt gun, or am I making a mountain out of a mole hill?

[gaijin]

COAL/mag length is going to be the same with most all common, popular bolt guns (Tikka/Ruger/etc) as the AR platform gas guns.
From memory 2.180” is about max for both gas guns and bolt guns.

[rjacobs]

You arent going to like the loads from the bolt gun in the gas gun anyway.

Gas guns dont seem to like the 140-143 stuff like the bolt guns do. They do better with the 120-123 stuff.

BUT if you want a longer magazine the KAC and Larue SR25 pattern mags are longer than the Magpul stuff.

[gaijin]

Same load (41.5 gr R16/140 gr. Hornady ELD-M, CCI BR2, Hornady brass) from 22" Aero 6.5 CM, M-5E1 "AR10" and 24" Howa chassis bolt gun. COAL 2.810" (I had COAL number transposed above- going from memory).
Velocity is 2740 for 24" bolt gun, 2725 from gas gun- losing 15 FPS for the 2" shorter barrel of gas gun.
(Black squares are 3/4" X 3/4")

Aero gas gun:



Howa bolt gun:

[rjacobs]

Just as a point of reference to what the lighter bullets do in gas guns.

Im pushing 123g AMAX with Varget(39.9g if I am not mistaken) to 2900fps out of my 22" JP barrel.

[JGault]

My AR10 tends to like the heavier projectiles.