Thxs. Pretty sure the subsonic rounds are the problem
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300 subsonic feed issues
- Thread starter tomusaf
- Start date
I only have an issue with the 300 whisper rounds that have been re branded as 300 blackout rounds. They are shorter and cause feed issues every few rounds. But as long as casing and projectile fill the mag like they are supposed to they cycle okay. I’ve found the sweet spot on my 7” sugar weasel and my 13” sugar weasel for supers and subs with or without a can. I just learned to stay away from the not really 300 blackout rounds and it’s all good. Also you can find a post with all the different manufacturers and who tries to pass off 300 whisper as 300 blackout on Q’s instagram just good information to have.
Yep mine is Anderson lower with psa upper 10.5 stainless 1/7 barrel. Shoots and cycles everything but subsonic
In order to cycle reliably with subs, you'll need to:
1. Check the gas port for size.
2. If you have an adjustable gas block, it would more than likely need to be wide open.
3. Make sure it has a standard carbine buffer. If the lower was built by Anderson, they typically tried to build as cheaply as possible, so it should have a carbine buffer already.
Subsonic ammunition is not the problem, the problem is that they gun is not configured to shoot subsonic ammunition. It can be difficult to get a .300Blk AR to cycle reliably with both subs and supers, without changing something between the two types of ammo. When a gun is comprised of cheap, unknown, or suspect parts, it gets even worse.
I have also seen quite a few chamber issues with PSA .300Blk barrels that crop up when attempting to shoot subs. They'll feed, but they won't quite chamber all the way.
1. Check the gas port for size.
2. If you have an adjustable gas block, it would more than likely need to be wide open.
3. Make sure it has a standard carbine buffer. If the lower was built by Anderson, they typically tried to build as cheaply as possible, so it should have a carbine buffer already.
Subsonic ammunition is not the problem, the problem is that they gun is not configured to shoot subsonic ammunition. It can be difficult to get a .300Blk AR to cycle reliably with both subs and supers, without changing something between the two types of ammo. When a gun is comprised of cheap, unknown, or suspect parts, it gets even worse.
I have also seen quite a few chamber issues with PSA .300Blk barrels that crop up when attempting to shoot subs. They'll feed, but they won't quite chamber all the way.
The PSA I had when I first got into 300blk I had to use the lightest buffer available for higher grain subs and they still would get stuck and not feed all the way every once in a while. Personally I found it easier to cycle 200gr subs vs. 220gr subs. The 220gr I still have to have my gas block as open as I possibly can with an H1 buffer all with Q and Noveske parts. The 200gr I can leave it right where I would fire 150gr supers and my buffer from the shorty stock cycles them all. Experimentation is the best outcome for me. I’m sure the gentleman before me will agree. Just check out different bullet grains with different amounts of gas if it’s adjustable and different buffer weights. That’s the cool thing about 300blk to me is all the different setups and changes that can be made. I had my 7” with a 1-5 twist set so low with 220gr subs when they impacted the target they didn’t barely leave a mark but with the same gun and ammo have pierced through the same AR500 steel target. It’s not an easy thing to pinpoint the sweet spot. But it is possible with decent parts, Time, and effort.
I have a 16 inch Carbine Gas system upper with a standard rifle stock and buffer system lower. It shoots Supers or Subs with or without a suppressor. My ammo is all handloads: 17.0 Lilgun with a 150, or 11.0 Shooters World Blackout and a 220grain coated bullet.
The bolt barely locks back on the last subsonic round shot without the suppressor, but has no problem with the suppressor. At 10.5 grains of powder the bolt will not lock back, but does feed and eject. At 11.5grains the round goes Supersonic.
As an aside: the Shooters World Blackout powder is very, very, incredibly Dirty in the Subsonics that I shoot.
The bolt barely locks back on the last subsonic round shot without the suppressor, but has no problem with the suppressor. At 10.5 grains of powder the bolt will not lock back, but does feed and eject. At 11.5grains the round goes Supersonic.
As an aside: the Shooters World Blackout powder is very, very, incredibly Dirty in the Subsonics that I shoot.
Im failing to see the issue then.
I have had no issues cycling in my 10.5" pistol. Nor has my buddy with his 7.5" with or without can. We both handload and develop our loads for the individual gun. We have come to the conclusion that factory sub ammo is loaded for a 16" bbl and when you use a shorter barrel, you get less velocity which affects function. We also use CFE BLK powder which was specifically designed for sub in an AR. It generates more gas than other powders. I believe if you use CFE BLK and tune it to 1050 or so for you length barrel, you won't have cycling issues. It may be the manufacturers use the fastest burning powder that gets their target velocity and it doesn't generate enough gas volume to cycle a short barrel.
For those of you that haven't tried CFE BLK for subs, you really should, I think you will be pleased with it.
I do use Lil'gun for supers.
Rosewood
For those of you that haven't tried CFE BLK for subs, you really should, I think you will be pleased with it.
I do use Lil'gun for supers.
Rosewood
