Hey guys,
I’m looking for a prebuilt 300 BLK upper in the 8–9.5" range that’ll be running suppressed 24/7. I have an LMT 8" barrel but can’t find a 7.25" PDW upper at a sane price, and I hate Q, so skip that route. My main question: is there a real velocity or performance advantage going from 8" to something like 9" or 9.5"? Also, how critical is an adjustable gas block on these short setups, especially for handling subsonics vs. supers? I’d love any brand suggestions that are decent quality without going broke.

Thanks!

What are you using to store a bunch of ammo but still portable?

I put the first couple hundred rounds through it today and it felt great. This does not bode well for my wallet. What should I get next? I have a can in the mail!

I only run LBP cans and the original rattler would not cycle w the ventum or b&T SRBS I have. I know .300 subs and flow through cans are a tough match but curious if yall have had success? Was hoping the longer barrel might help?? I handled one and now want one, but don’t wanna waste $ either. Thanks! Still rocking my griffin factory build too

Recently acquired an old Bushmaster XM15 in 5.56 with a carry handle and I was thinking of turning it into a 300BLK rifle. What exactly do I need to change out, aside from the barrel, for it to work?

I shot 50 rounds of Magtech Tactical 200-grain subsonic 300 Blackout today. I experienced 3 failure to feeds (FTFs) and noticed an abnormal amount of brass shavings on the bolt carrier group (BCG). The spent cases had two nicks, as shown in the attached photo.

Setup:

• Barrel: Faxon 7.5", 1:5 twist, suppressed
• BCG: Daniel Defense
• Buffer Spring: Springco Yellow
• Buffer: 3oz

I’m looking for advice on how to address the following issues:

1. Failure to Feed
2. Excessive brass shavings
3. Nicked spent cases

Could this be related to headspace, buffer weight, or extractor/ejector wear? Any suggestions on troubleshooting and potential fixes would be greatly appreciated!

Closer look on spend cases: https://imgur.com/a/aWbTjBs

Yeah I know this is not ideal, and I should have a high back pressure can.

My question is, has anyone built this setup to successfully cycle subs (in my case 220 grain aac) simply by adjusting reciprocating mass parts. I have a law folder with the low mass plug, the gas system is as open as it can be, a standard weight bcg, sprinco Yellow buffer spring and the Kak 1.7 oz buffer.

This ended up being a single shot, so I took an old buffer and removed all weights from it. I got it to cycle maximum 3 times and other times it'd short stroke or ALMOST pick up a round, but still ftf, and I'd have to eject the mag.

My last options before I have to drill out gas ports and get creative with gas tubes, is a Kak low mass bcg and the Nemo flatwire spring.

If anyone else has any other ideas or something that has worked for them, I'm all ears.

Also side note... There's a shit ton of unburnt powder that gets shit back into the chamber, but I'm assuming that's to be expected since it's a 6 inch barrel with like... What 3/4 inch of dwell time?

piecing together this pistol, still deciding on brace setups. Between Maxim Defense SCW and just get a folder with a regular sba brace, curious what you guys think a good brace setup would be if not the 2 i mentioned.

-PSA 7.5 inch -Holosun 510c with magnifier (yes i know the magnifier is useless with subs, just really like the optic setup and i can use it in the future on other builds)

-Have Geiselle SSA-E on the way -Will be buying Diligent Defense inticer s TI soon. otherwise pretty basic just poormetto budget build.

I know this gun was made to have a suppressor and am wondering if anyone has any recommendations on which one to buy. I’m kinda stuck between the Otter Creek Labs polonium 30, OCL hydrogen K, and the dead air nomad 30. Any advice is appreciated!

Building a .300 Blk pistol, 8in Faxon barrel with non-adjustable gas block. What weight buffer would you suggest? Gun will be shot suppressed 100% of the time.

Has anyone chrono’d a 4.75” with subs? What fps with what gr? Thanks in advance

Left to right.

POF 308 SFAR with Pulsar Talion XG35. Aero upper 300 BO with Spike lower and Rattler V2 25x385 (missing eye cup, lost it last night). V Seven upper and lower with Infitac FAH25.

The 308 has turned out to be my fav, but the middle rifle is a soft shooter. The VSeven is super light, trying to soften the recoil still.

It’s me, again lol. See my post history about my post I made yesterday

Quentin Defense 7” 1:5 barrel Q Adjustable Gas Block (fully open) Carbine Buffer / Normal Spring (3oz) 2A 200grain subs (https://2awarehouse.com/capital-cartridge-300-blackout-200gr-fmj-subsonic-new-brass-50-round-box/)

Biggest issue I’m having it FTF and FTE issues. Sometimes it’ll act like a bolt action gun, sometimes it’ll shoot 2-4 rounds and then go back to FTF, and other times it’ll dump an entire mag lol. Cycles supers perfectly fine - subs not so much. GB is perfectly centered also.

Issue is I had a 300blk deal back in November that was similar to this and I had the same issues that I’m having now. Wanting to try a heavier buffer and springco yellow before I buy factory S&B subs. I just fully assume these rounds are junk but I’ve heard many good things about this ammo on Reddit.

I did try a box of factory subs and it cycled fine but I have 400 rounds of these 2A subs just sitting around so I possibly will continue to see if I can work them reliably before I move on to factory rounds. Springco Yellow Spring + Heavier Buffer may be the solution?

Saving brass to start reloading soon and these 4 marks are pretty consistent on the brass with my Aero upper. Anyone have an idea why, how to fix it and if the marks will mess up reloading?