300BO subsonic question

General Discussion
21

With a can subs should run. You may need to change the buffe and/or spring. Which pistol are you looking at?

22

I made a buffer weight change to H2, and that allows me to reliably run subsonic 300 Blackout WITHOUT a can

As delivered it would short stroke with subs. While it ejected the spent casing, it never picked up the next round from the magazine

The heavier buffer weight also smoothed the pistol out and removed some of the harshness

23

Usually an H2 is where short 300blks end up. My first sbr i ended up with the Spikes T2, which is between an H and H2.

24

I was thinking just the standard PSA 300 blackout pistol with a 7.5 inch barrel. Perhaps this one:

https://palmettostatearmory.com/psa-7-5-pistol-length-300aac-1-8-phosphate-6-lightweight-m-lok-moe-ept-sba3-pistol-5165449201.html

Since I would be using it as a home defense weapon, it’s very important that it will be able to run reliably using subsonic ammo with my Silencerco Hybrid 46 suppressor.

I was also looking at the Sig Rattlers, but that price tag is making my eyes pop out of my sockets :rofl: I have had great experiences with other PSA rifles, including an AR-10 and an AR-15. I was thinking it would be nice if I could get a reliable PSA 300BO for a fraction of the price of the Sig.

Thanks.

25

Good to know. I will definitely keep the H2 in mind.

26

Pistol length gas systems are even shorter than carbine systems, and notoriously harsh.

Using a heavier buffer requires more gas pressure to build before the cycle begins. That increased pressure is similar to running a can. In all honesty, you could run a H3 buffer for even better results.

I only run Armaspec SMBs in my AR builds, so a buffer weight swap is more expensive. I tend to stick with what works but will probably buy a H3 and experiment with it in all my ARs.

27

Edited for final weight.
10.5 had no issues cycling 208gr subs. Recoil was harsh with the KAC blade.
Ejection was missing the deflector & going over my right shoulder.

I took an H2 buffer (hard to find at the time 7 or so years back). Took it and the stock buffer from the PSA kit apart & blanced the weights between the 2 as best I could. I think they are 0.2 oz different.
Recoil feel reduced & ejection tamed to 2:30-3:30, muzzle being 12 o’clock.
1 = 3.7 oz
1 = 3.9 oz

No can, stock fixed gas block.
Just my experience in this realm.