.308 Subsonic load group sizes

[TOP PREDATOR]

would love to see some pictures or sizes of groups using .308 subsonic loads before i give it a try and doing the PIA of running 3 dopes on my rifle (subsonic, 110vmax, 165sst).

anyone running subs have pictures or care to post group sizes at various yardages (100 / 200 / 300) and drop data?

 

[mtrmn]

I have no pics, but the absolute BEST group in my brief experimentation was about 2" at 100 yds. This was a Bushmaster BAR10 308, 20" bbl, 1/10 twist. (this is the early version of the present RRA LAR8) Remington Core-lokt 180 gr with somewhere around 10.5 gr Trail Boss. POI was about 12" lower than my normal POI at 100 yds--I'd hate to see the drop at 300! IMO--if you have visions of hunting with subs you need to forget about the 200/300 yd performance. Mine were showing signs of losing stability at 100. They were plenty stable at the muzzle though, which is where it really counts when trying not to destroy your suppressor.

I just stick with the normal full-house loads and my rifle still sounds about like a non-suppressed 22LR, and I get full bullet performance.

 

[TOP PREDATOR]

^ thanks, new to the whole centerfire subsonic stuff, after a bit more reading up i'm guessing 150Y max with a good load / barrel twist match.

 

[nfoley]

Played a little with trail boss and best groups I've seen are also 2-3" at 100 yds. I can't seem to get rid of the significant drop in velocity with each subsequent shot. Tried lube on the bullets, still see it. After about 5 shots I'm getting pretty worried about sticking a bullet half way down my barrel. And it's a pain to have to clean every 5 rounds.
But it's fun to shoot with such a minimal report.

 

[mtrmn]

Yes and 150yd is pushing it in my opinion unless you can find a good bullet that your gun likes. I know that millions of game animals have fallen to subsonic speed bullets ever since guns were invented, but I'm pretty sure the ranges were short in 90% of those. Bullet placement is key, and it's pretty hard to place a keyholing bullet.
I tried to get 224 varmint bullets to perform when fired in water at subsonic speeds and got nothing. Other than the rifling marks, I'm pretty sure I could have loaded the bullets up and fired them again. I did this using 6 milk jugs full of water lined up at about 20 ft from the muzzle. A normally explosive Vmax just punched a clean hole through the first 3 jugs and stopped in the 4th. Needless to say the 30 cal jacketed bullets had similar results, just a little more impact due to their weight.
There are some bullets out there that are made for subsonic use that the makers pretty much guarantee a mushroom/expansion. They are pretty pricey. (outlaw state bullets? that seems to come to mind) But normal jacketed hunting bullets will not perform at these slow speeds. This is why everybody says to go with the heaviest bullet you can stabilize so you can take advantage of the better retained energy. I've pretty much concluded that a flat nose cast bullet would be best for hunting-the flat nose adding some shock value.
I don't know what twist rifling you have, but the faster the better. ALWAYS do a test of your rounds without the suppressor to make sure the bullets are stable enough to not give baffle strikes. I did this at the muzzle as well as at range--at the muzzle is where it matters most.
I'm sure you know, but there's a lot more info from people a lot more experienced than me in the suppressor section. And a lot of loading info for subs in the stickies. I just experimented with the subs for shits and grins, and keep a few around for impressing my buddies with suppressor demos. I don't load any for serious use-it's plenty quiet with full power loads when I need results on the other end.
I'm not trying to discourage you, just reporting real results and maybe help you out. YMMV

 

[MontanaMarine]

220gr hornady RN and Unique. Rem 1/12 bbl. 100 yards. As you can see the bullets were wobbling into the target. 1/10 twist or faster would have probably achieved stability.

 

[forrestgump01]

One of the keys is to use a ROUND NOSE -FLAT BASE bullet. Regular bullets don't want to stabalize at slow speeds because there center of gravity is more towards the back of the bullet.
I use a 170. Grn 30-30 cal bullet -round nose flat base-with 10.5 grns of trail boss in a 1 in 12 twist. Groups are in the 1.5 to 2 in range at 100 yds. Takes 15 mn elv from my normal 100 yd zero.
Just remember your ballistics are basicly equivilent to a 40 cal pistol.
The trail boss burns really nasty and makes cleaning a pain. One thing I have found is the more you shoot and the nastier it gets the better it shoots. They are fun but eventually you will find you almost need a dedicated rifle for sub loads. If I had listened to a wise man named huskey I would have built a good 22 bolt gun with can and sub ammo to start with and not wasted a lot of time and frustraition ! Hope this helps.

 

[TOP PREDATOR]

thanks for the responses.

i was on the fence / on the bandwagon of putting together a .300 blackout, but might as well consider going with a dedicated .308 subsonic as it'll be a bolt. i'm not wanting to run a suppressor at this time.

interestingly, i bumped into a guy that loads .308 subsonics yesterday, he mentioned that with using trail boss vs tightgroup, the muzzle may have to be lifted in the air to get the smaller volume of powder to the back of the case for better ignition unless using some sort of polyfill.

anything to that?

or is it just start with the recommended higher charge of trailboss, tightgroup, red dot, and other suggested powders and stop reducing once around 1050FPS and not worry about where the powder lays in the case?

as far as the load data, i'll refer to the subsonic loading data posted in the other thread(s), with my current .308 and see if it's worth me to pursue.

sorry for the questions, being a newbie to SS loads, i don't want to do anything that may create an unfavorable condition.

 

[mtrmn]

thanks for the responses.

i was on the fence / on the bandwagon of putting together a .300 blackout, but might as well consider going with a dedicated .308 subsonic as it'll be a bolt. i'm not wanting to run a suppressor at this time. I suppose you're getting ready to get a suppressor in the future? Otherwise I don't understand why you'd want a dedicated subsonic gun, but that's really none of my business anyway. Subsonic 308 without a suppressor will still be pretty loud.

interestingly, i bumped into a guy that loads .308 subsonics yesterday, he mentioned that with using trail boss vs tightgroup, the muzzle may have to be lifted in the air to get the smaller volume of powder to the back of the case for better ignition unless using some sort of polyfill.

anything to that? Yes there probably is merit to this, esp if you use something besides Trail Boss. However I have no experience with doing it.

or is it just start with the recommended higher charge of trailboss, tightgroup, red dot, and other suggested powders and stop reducing once around 1050FPS and not worry about where the powder lays in the case? This is what I did, and lowered the charges until I lost the supersonic crack. People do it this way to avoid a too-light squib load that might leave a bullet in the barrel.

as far as the load data, i'll refer to the subsonic loading data posted in the other thread(s), with my current .308 and see if it's worth me to pursue.
That would be wise, better than building a dedicated gun only to find out that it wasn't going to work for you. Hopefully your present gun has like 1/10 twist or faster?
sorry for the questions, being a newbie to SS loads, i don't want to do anything that may create an unfavorable condition.

If you DO build a dedicated gun especially for subs, I suggest getting the fastest twist barrel for those heavy bullets. You need to understand I'm not an expert at this or anything. I've only done a little experimenting with subs, but enough to know I don't really have a PRACTICAL use for them. There are many others on here that have far more experience/knowledge than I do on this subject. I'm just trying to help you out with the little practical experience I have.