308 subsonic

[xat130]

Thanks. I'll check with LS to see if they have those cases available.

Great info in this thread!!

[xat130]

Looks like they are not making them anymore. She said it was not cost effective.

[dick]

JF had it right on the first post 5744 or 4759 is were it is at. I prefer the
225 gr outlaw over 12 gr of 4759 and a large rifle magnum primer. Works great out of 20" 1/10 and 1/11.25 twist Armalite and DPMS with shut off gas
systems. SUB MOA easly attainable. With an open gas system I have tried 4759, 5744, 1680, 2015, TAC, 2015, trying to cycle the rifle. I was able to easly eject the spent case but would not pick up the next. I think this would be achievable in a carbine length gas system AR-10 type platform. I have done the mentioned with a .310 225 gr outlaw with 12gr 5744 and FED LARGE RIFLE MAG primer 7.62 x 39 WIN case, SUB-SONIC, cycles 16" carbine 7.62 x 39 Modle1sales upper unsuppressed.

[Artful]

Originally Posted by xat130

Looks like they are not making them anymore. She said it was not cost effective.

Shame, I llike them - I guess if I was still looking to play I would look into the filling with hot lead and reboring the powder chamber to the spec's I wanted. Reduced capcity cases in 308 are the best solution.

[rdwehus47]

hey been reading the forum

i have used to great results, trailboss powder for subsonic 308 loads.

i currently used win 748 for the 150g horn sst projectiles. (47g of 748)
when i put trailboss in my dillion powder measure, didnt change the setting from the win 748 and tried a charge, it measured 14.6g. At that point i was ok with the case volume.

Started testing 10g 11g 12g 13g loads

with my YHM can, the 10g with 168g btsps works great - prints 4 holes at 50 yards... no issues what so ever.


when i tried the 180g btsp projectiles however, they where keyholes with 10g of trailboss..

i havent tried going up powder or down to 8gs, any input?

the trailboss powder looks like dounuts...

just wanted to pass this a long...

thanks

Robert

[HUNTER2]

You will be a lot safer trying the different bullets WITHOUT the suppressor. Until you get the speed you desire. What twist are you using? Maybe not fast enough for the longer bullets, or not fast enough yet. Nearly ruined a good suppressor with some long bullets going too slow. Those things are precious!

[atrdriver1]

Rifle: DPMS LR308 16” 10 twist
Silencer: HTG M30
Elevation: 5500ft

The load I have settled on is:

9.9 gr Trail Boss with a 175gr Sierra Match King projectile.
Brass: Winchester with flash hole drilled out to 9/64”
Primer: Rem magnum

This gives me appx. 1000fps which keeps me sub sonic all the way down to 0 degrees F.

I started out using Win 231 because I have a bunch of it for my 45acp loads. I found that it was not consistent. The velocity would climb as the barrel warmed up as much as 200fps. Accuracy was very poor as a result.

Trail Boss is MUCH better. The temperature of the barrel seems to make no difference on the velocity. My typical extreme spread is about 60fps with a standard deviation of about 25.

On my most recent trip to the range, I shot 4 groups of 5rds each. The average for all four groups was .74moa. Surprisingly, this same rifle typically shoots 1.25moa with full power match grade ammo.

I did try this same load in brass with standard flash holes and the extreme spread rose a little to 80fps, but that was only one shot string of 10rds, so it is not conclusive by any means.

2 other projectiles I have tried in this barrel and that stabilized just fine were the 178gr AMAX and the 200gr Lapua sub sonic.

I experimented with loading the bullets backwards to explore the possibility of using even heavier projectiles, but they would not feed from the magazine.

[hopps]

atr, does your dpms cycle with that load? Does it eject but not pick up? I am curious because I am trying to decide if I should go carbine or pistol length gas with the .308 I am building and want to do some subsonic stuff with...

[thehouseproduct]

I am also curious about this. I have a LR308B with an 18" barrel with a carbine gas length system. I think I could probably get subsonic easier with the shorter gas system.

[Romeyo]

Unfortunatly I can't really add something helpful to that thread so far, but I'll give the european made reduced capacity brass a try in the near future and will share results.

What I'm interested in is the fact that many shooters recommend loading long boat tail bullets base-forward in subsonic catridges.
Has anybody maybe did a BC comparing of this setup? I think it would be really interesting since at subsonic velocities base drag comes more into account and tip shape less because it hasn't to deal with supersonic shock waves.
Although I wouldn't expect them to perform better base forward, but maybe near to equal?

Also, what's about accuracy? I read that long boat tail bullets (and a base-forward scenar/SMK/... got a heck of a BT then...) tend to get destabilized by muzzle blast? But that's maybe not that of an issue since longer barrels and fast burning powder don't generate much pressure at the muzzle...

What do you think?