I have a friend that built an AR pistol in 300 Blackout, he is having trouble getting it to feed sub-sonic loads in the 1000-1100 fps range, gun functions flawlessly with regular powered loads. Any suggestions on quick burning powders or possibly changing buffer weights and springs would be greatly appreciated. BTW, barrel length is 7.5"

H110 is the powder to try

Any recommendation of starting grains on a 190-200 grain boolit?

10.9gr of 1680 under a 220 Matchking is a good subsonic load. I have not tried it in a pistol, but in 2 different carbines it ran flawlessly. 1680 apparently generates enough gas volume to reliably cycle the action

I have heard the Lehigh Defense bullets are good on game even at subsonic speeds, but have not yet tried any of them.

does it have an H2 in it, try a carbine first.

The lehigh bullets have been perfect so far this year.

We are having trouble getting pics off my iphone into photobucket for some reason.... the email transfer keeps failing, but I have more pics from this past weekend.

Evidnetly 123 yards is about as far as one wants to go and hit bones.... did a penetration test on a doe, lot of angle, entered behind liver, got liver, lungs, heart and broke off side shoulder at the knuckle joint and thats where the bullet was in the shoulder meat...

I have heard 1680 is the ticket for gas guns. Not sure if that includes shorties.

Feed or cycle, big difference?

AA1680 is what gets my subsonics running a gas gun. 10.5-11 grain range.

Another hoorah for aa 1680 powder. I have a 10.5 inch Noveske upper with an H2 buffer and it has never not fed my subsonics and supersonic reloads and always locks back the bolt after last round fired.

Only thing I've heard is 1680 is not that quiet of a powder even in a can... guess you caon't have it all.

I"m fairly well thinking the port on my Rock tube, will end up being opened until I can get it to cycle with H110 or LIl gun.

In the meantime noise is driving me nuts with my can. Well under supersonic speed, even for the temps, the load I shot friday night should have been sub to -20.. it was probably 65 when I shto it and it was the loudest sub I've heard in a long time.... 2 other hunters about 600 yards away heard it clearly.

Next evening a buddy used same and he was the one that herad my shot, I NEVER heard his, he said it sounded like the normal loud pellet gun...

Who knows...

Not for subs. H110 may or may not work for subsonics, depending on the gun, and isn't the go-to powder by any stretch.

If you're having function issues with subs, start with AA1680 powder; that's what the system was designed for.

If you can get the gun to cycle, Lil'Gun or H110 are a bit quieter; Lil'Gun is the quietest of these three. I found that mine will run subs with Lil'Gun and jacketed bullets as light as 175 grains, but won't cycle cast bullet subs with Lil'Gun or H110 even with 240gr bullets. AA1680 runs great with everything.

For really quiet subs, you have to give up semi-auto function. Any fast pistol powder between Bullseye and Unique works for that, and is a lot quieter, but turns the gun into a straight-pull bolt action.

I still bet that with working on the gas port you can run subs with the quiet powders. Almost has to be. But I've been wrong 3 times in my life... LOL.

Is he running an adjustable gas block?

I'd think that would obviously be the way to run, get an adj block, and then set it basically in the middle, then drill the port until it works...

what do you like best for the 110 supersonics in a 10 inch barrel? Lilgun or H110 or ?

No, was hoping to get it to be able to run both ways without changing anything.

I appreciate all the suggestions, looking to find some AA1680 right now.

No. You'd need an even shorter gas system, and a huge gas port, and probably a lightweight bolt too. Anything that would cycle with the fast pistol powders would have to be limited to those loads exclusively, and couldn't handle supersonics.

You'd have to try those loads to feel the difference. The reason they are quieter is the pressure curve is very short, and the powder/gas volume is much smaller. For example, sub loads with Unique take a bit less than half the powder of comparable AA1680 loads. Bullseye loads use about 1/3 that much.

Both work well, and give top velocities. H110 has more blast and noise, but runs well all the way up to max. Lil'Gun is less blasty, and produces top velocity at lower pressure than H110, but can produce large extreme spreads when pushed too hard.

I prefer Lil'Gun for less blast in the short barrels.

That's how it should be. If the gun "needs" an adjustable block, or different buffer, etc, it's set up wrong.

My Noveske 10.5 inch uses a pistol length gas system, cabine buffer. Cycles and locks back on empty every time. I use H110 for my supersonic and AA 1680 for subsonic. It works flawlessly with or without a suppressor for both supersonic and subsonic reloads. I went with a Noveske Factory rifle as I figured they had already been down the road and found a solution to most cycling issues.

I wonder what Barnes loads under their Vor-TX bullet? The factory Hornady 110 Vmax in my gun is a 5 inch wonder, the factory barnes 110 Vor-TX is a 1.5 inch deal. Also the Barnes shoots thru stuff quite nicely.

That actually would work, but not for most.. I see no reason to run supersonic at all in the 300/221... if I"m going to run super... I"m going to run x39 instead...

So if I can get my subs to cycle an AR, with the quietest powder that will be cool.

A light carrier and so on, all makes sense, you should be able to make it all work with the right porting.

I'm not at all up on gas system lengths but shorter does make sense. I"m hosed to a carbine length one thoug at the moment due to the rock barrel setup.

With powder availability (or lack thereof) being what it is, seems running an adjustable block wouldn't be a bad plan.

One could say exactly the opposite, why use a different gun in 7.62x39 when you could just switch mags and run supersonics in the 300 Blackout, and get pretty much the same ballistics, with better accuracy?

Best of luck to you on that, you'll spend a lot of money chasing that pipe dream. You might want to actually try some of those fast powder loads before committing to it.

You're right about being hosed with a carbine length gas system; even a 16" barrel is better with pistol length gas.

the 300 makes a lot of sense in 10.5 inch SBR's and pistols and I guess suppressed. It makes a lot more sense in a short barrel both super and subsonic than the 5.56. The 5.56 makes more sense in a 16.5 and above to me. A 10.5 inch pistol that produces 2100 FPS with a 110 grain bullet is an effective sub 200 pound game getter under 100 yards or so is my contention, similar to a 62 grain bullet at near 3000 to my findings. One thing about the 30 cal 110 Vor-TX, makes a bigger exit hole than a 223 TTSX.

I managed to acquire some 240gr Matchkings, and I'll probably experiment with them in sub loads. It will be interesting to see how they do out of a 1 in 8" barrel.

I don't see the 300 as a replacement for the 5.56, rather it offers something the 5.56 does't, a platform to launch 200+ gr bullets subsonic. While running an SBR with a can would make for a nice compact rifle, I don't see the 16" barrel with a can being a deal breaker for those that don't want the added tax stamp of an SBR.

I used to have a 16 inch noveske upper. With can attached it was out of balance. I then got the stamp for SBR for my lower. Bought a 10.5 inch noveske upper and sold the 16. Everything is good now.