I've had my 300blk for a little over a year now, and it has basically sat in my closet for most of that time due to having some cycling issues while running suppressed subsonics. Very hard right now to troubleshoot the issue with the current ammo situation

Being new to the caliber, I'm really having trouble diagnosing it... Even after doing a bit of research.

Supers and subs run fine unsupressed... Super also run fine suppressed, but the issue is with suppressed subs.

Most of the issue I ran into were what I believe is short stroking, which leads me to believe its having undergassing issues with suppressed Subs... But wouldn't that issue be present without the suppressor?

Sometimes it will fire 5 rounds flawlessly, with shells ejecting roughly at 3 or 4 O'clock position. But then just choke with short strokes or bcg not fully locking.

Just wanted some opinions before dropping a couple hundred dollars on stuff that may not solve my issue lol.
But most likely assuming I will need an adjustable GB, and possibly a different weight buffer... Just unsure which weight I'd need.

Rifle has:
8.2" Roscoe Bloodline barrel
Ballistic Advantage .750 Gas block
PSA "Full Auto" BCG
BCM M4 Buffer tube kit (Unsure of what weight buffer they include in their kits )

The other way around (subs only works suppressed) is commonish.  I guess I'd try a carbine buffer if its got a heavier one.

If it runs subs unsuppressed then the suppressor should increase gas impulse dwell time.  But ejecting at 3-4 o’clock suppressed doesn’t sound over-gassed or too much bolt velocity.  It could be you are getting enough crud from suppressor blowback back into the magazine that it creates a feeding issue.  Look at magazine feed lips, spring tension, and how shiny or dull your cases are.  Trying a different brand of ammo might be a good thing to see if it behaves any differently.

Adjustable gas block could be used if it is actually over-gassed, but that really doesn’t seem to fit. If it’s under gassed you’ll need to open up the gas port.  If that happens adjustable gas block could be useful for supers suppressed.

The bolt is moving too fast to do its job.

It just looks like it is short stroking.

Get an H3 weight buffer.

And get an adjustable gas block.

"They" should just include an adjustable gas block for all 300 BO uppers.

kmtactical.com has H3 buffers for $18; currently OOS.

If that was the case wouldn't it choke with supressed supers too ? The bolt would be moving even faster in that case.

Honestly that doesn't make a lot of sense, and we could debate what's happening but the easiest way to
fix it is probably

1. install adjustable gas block
2. close off gas block
3. load 1 bullet into an empty mag
4. gradually open gas block and shoot it
5. repeat step 3 until it locks back

Probably wouldn't hurt to weigh & identify your buffer so you know what's in your AR. Maybe it says which buffer is included in the kit you bough on the vendor's website. You could call or email them to confirm.

Thread closed.

OP froze to death riding his chopper wearing only chaps.

??????
I'm alive... I just forgot about this post.

Debating on just selling the upper and my 500rd case of supers.

Right now is just not a good time financially to be experimenting with this round.
I don't reload, and factory .300blk wasn't exactly cheap before the pandemic craze... Now its just plain ridiculous, when you can find it. ??