300BlkTalk

My 300 BLK build is a BA 8.4" barrel with a Standard pistol length gas system. Not adjustable. Also I am running a standard Toolcraft BCG, I do have a Bootleg BCG for the pistol if I ever suppress it. I also have a LaRue MBT-2s trigger. The first time I went to the range with the gun I had numerous problems, failure to feed and last round not locking back, etc. I scrubbed the chamber extremely well, and changed the Geissele Super 42 spring and H2 buffer to a standard carbine spring and standard buffer. I just returned from the range and was delighted that I only had issues with one brand of ammo. The 205 gr Sig Sauer Subsonic hunting ammo. This ammo was in an DH Magazine branded 300 BLK. This ammo is really strange looking, it has a relatively flat point with a plastic tip and the cartridge is about 1/8" longer than the Fiocchi 220 gr Subsonic I also shot. The Fiocchi was an absolute joy to shoot, virtually no recoil and much quieter than the supersonics I was shooting.

The issue I had with the Sig ammo was the first two rounds would fire and chamber, then the third round would jam with the point up in front of the chamber. I also had a few instances of the last round (even with Supers) not locking the bolt back. Not regularly but about three times with 9 different magazines. I have a Nemo light weight recoil spring, would that help the issue? Do you think the issue is magazine related? This magazine has a red follower and doesn't seem to be as anti tilt and smooth as my 300 BLK Lancer magazines. I didn't get a chance to try the ammo in multiple magazines as I only had a few rounds of this ammo (over $1 per each), but I will schedule another range trip to try any ideas you suggest so I can shoot this ammo.

The other Subsonic ammo, the Fiocchi was so nice to shoot, I started looking at suppressors on the way out of the range. I'm looking at the SilencerCo Harvester 300 suppressor. What are your feelings on this choice?

Thanks, Rick

Two extremes, kind of. Same fix sort of.

If the bolt climbed over the base, it’s usually because the magazine can’t keep the pressure up fast enough. A little more buffer slows things down and a 300 Blk mag keeps the drag down and the pressure up.

If the bolt caught the base and jambed the tip into the top of the barrel extension, it’s usually the bullet bouncing off the front of the magazine. A little more buffer slows the bump down and a 300 Blk mag has a wider opening with less to bounce off. A shorter cartridge OAL releases from the mag faster and makes a difference here too.

In general, without changing gas levels, a heavy spring and lighter buffer speeds it up. But a heavier buffer slows a stock spring down. Less bouncing and smoother.

Assuming enough gas to lock the bolt back and enough recoil spring to strip a round off.

Maybe just try the H2 again with the stock spring. Or H1 till it all breaks in. A new setup can be pretty stiff for light loads. I’ll run the guns wet when they’re new like that.

The Harvester isn’t full auto rated. A friend destroyed his because if you can you probably will. Silencerco fixed it even though they knew. Crazy awesome warranty. Course that was 556 not 300 Blk. Ideal for a lightweight hunting setup but maybe not the best on an AR.

Thanks for the information CDL. On my examination while cleaning the excess CLP up (ran it very wet), I found I was not using the stock spring, rather a Damage Industries Enhanced Chrome spring. On my next range trip I plan to use the stock spring and the Lancer 300 BLK magazine for this weird shaped Sig Sauer cartridge. Also I'll take along the NEMO light weight spring and a H1 or H2 buffer and try them too. I don't do mag dumps so I'm thinking the Harvester might be ok for me. On a side note can I use the 30 cal silencer on a 9mm PCC too?

Thanks again for the info.

Rick

30 caliber cans are not a good idea with .355-.356 bullet diameter! While there may be a can that has sufficient clearance, not likely a workable option. Short answer is..Nope. If you want to use on a 9mm PCC, a larger caliber or a modular type will be a safe choice.