Think I have a gas leak.......

[ABNAK]

Shot my Radical Firearms 300BLK (10.5" barrel, pistol length gas) yesterday for the first time. Was using 110gr TAC-TX. Fired about 60 rounds but it functioned without any problems. Only thing was there was a little more "blowback" than I'm used to with 5.56 and being a lefty you tend to notice it easier. Brass was also leaving a helluva mark on the deflector, not just the normal little dings you usually see. There was a copper-colored gas residue all over the top and sides of the barrel behind the gas block, on the gas tube, and inside of the FF handguard. None on the bottom of the barrel. Reminds me of what I saw with the LWRC I had years ago when the excess gas residue spewed all up under the rail and gas block.

So, evidently I have a gas leak. Going to my buddy's today and remove the FF handguard to inspect. Anything I should be looking for specifically? I know the obvious is looseness, but aside from that. What would be the fix? It's either leaking around the gas tube insertion point or between the barrel and gas block, correct?

Odd that it functioned fine with a leak like that. Could the heavy brass marks on the deflector be caused by less recoil/extraction/ejection force? On every piece of brass there are two little "snakebite" marks on the case neck, just so happens to be the width of the locking lugs on the barrel extension. Is slower and weaker extraction causing the brass to hit the "teeth" on the barrel extension instead of clearing them as the case is extracted?

[misfit47]

It'll run with that leak because it's over gassed. Check for fit of gas block to the barrel before locking it down. If you're worried about the brass marks on the deflector, apply some velcro to it. If gas block is really loose, either replace it or try sealing it up.

[SulzerFirearms]

To me it just sounds like your gun is over gassed. The fit of the gas tube in the gas block and the gas block to the barrel is far from air tight. If it is functioning fine I would keep running it. The carbon will eventually seal itself.

[HCrum87hc]

To me it just sounds like your gun is over gassed. The fit of the gas tube in the gas block and the gas block to the barrel is far from air tight. If it is functioning fine I would keep running it. The carbon will eventually seal itself.

This was my thinking as well. You could try a barrel with a smaller gas port if it really concerns you.

[bandw1dth]

I had a similar problem where there would be gas leaking out from where the gas block mated to the barrel. I just kept shooting it and a couple of hundred rounds later the carbon sealed the gas block to the barrel.

Just keep shooting I think you should be fine. That or get a clamp on adjustable gas block and tune the rifle to your load. I recommend SLR Rifleworks gas blocks.


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[ABNAK]

Well I went to Primary Arms' website (where I bought it from) and they sell the Radical Firearms gas blocks by themselves, so I read the reviews. It seems there are fit issues with the gas blocks to where some buyers had to sand the gas tubes to get them to fit or the blocks were otherwise out-of-spec. When my buddy and I looked at the gas block/gas tube interface there was a c-hair of a gap, i.e. it didn't appear to be an uber-snug fit. We removed the gas block and there wasn't any residue where the barrel and gas block meet; it appeared to be coming out of the spot where the gas tube goes into the gas block.

Now Radical Firearms has a limited lifetime warranty, but after speaking to Primary Arms they said they'd simply contact Radical and let them take care of it. Not sure about shipping costs either. It would also no doubt be replaced with another Radical Firearms gas block (duh!) and whatever fit issues were present would not necessarily correct themselves. So the old adage of "If you want it done right do it yourself" came to mind and I ordered a BCM gas block and pistol gas tube.

Yep, it's over-gassed alright. Radical Firearms advertises the port as being 0.750", but it must be a misprint as there's no way it's 3/4 of an inch wide! Probably 0.075" is more like it. This is my first foray into 300BLK so I'm not familiar with what is a "normal" gas port size for that caliber. No doubt it is geared for subsonic loads. So I also ordered an H3 buffer and I think I have a blue Sprinco spring but haven't looked yet.

If the new BCM gas block/gas tube combo doesn't fix the leak problem I'll sell the damn thing because with the shit blowing all over the barrel and handguard I might as well have a piston gun!