Sanity check on IMR 4895 load for 308 gas gun

[JimGnitecki]

I am finding conflicting information on safe and desirable loads for IMR 4895 (NOT H4895 ! ) at multiple loading manuals (IMR, Sierra, etc).

For use in an LMT MWSE 308 semi auto, what is a safe range of ladder loads?

My specs before adding the IMR 4895 powder:

- Lapua 308 cases
- Winchester Large Rifle primers
- Sierra 175g Matchking HPBT
- .003" neck tensión vía Redding bushing
- 2.810 to 2.820 allowable COAL (Pmags accommodate 2.820" max), because the bullet tip lengths vary, but actual COAL running 2.811" to 2.815" (Base to ogive = 2.212" at COAL = 2.811")
- Headspace 1.621" (provides .003" clearance with chamber)
- Bullet jump of .023 to .033 allowable range (can't get smaller because limited by Pmag COAL capacity), but actual of .028" to .032"

I'm thinking of ladder test powder weights of IMR 4895 =
40.0
40.5
41.0
41.5
42.0

Sensible and undamaging for a direct impingement gas gun?

Jim G

 

[Heman]

Re: Sanity check on IMR 4895 load for 308 gas gun

Nothing special as those are standard M1A service load charges, 41 or 41.5 seems to be the sweet spot with that bullet and powder. In my rifle it's 41.5gr. You will be safe just watch for pressure.

 

[Ballistic308]

Re: Sanity check on IMR 4895 load for 308 gas gun

42.1g of IMR 4895 in a Lapua case at 2.805" COAL. That is the OCW.

ETA: Here are the known OCW load from Dan Newberry's website. Since you are using Lapua brass (the listed is in Winchester brass) it will be .3g less than what is posted.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">308 Winchester using IMR 4895
150 grain bullet, 46.6 grains (extrapolated from following loads, untested at this writing)
155 grain bullet, 45.6 grains
168 grain bullet, 43.6 grains
<span style="color: #990000"><span style="font-weight: bold">175 grain bullet, 42.4 grains</span></span>
178 grain bullet, 42.0 grains</div></div>

 

[JimGnitecki]

Re: Sanity check on IMR 4895 load for 308 gas gun

Thanks, guys! This reassures me.

Jim G