fiftyohm

Yup. While function is now fine, even with low pressure stuff, but there is no doubt upping the mass would make it more pleasant to shoot. You had even less dwell than I did at the start, so your final port size makes perfect sense. I guess I could rent a Ditch Witch and bore a honkin' huge hole like you at some point, too! (The can will be no help as it's an OSS with little to no back-pressure.) The way you mitigated the charging force is very interesting. Good stuff - thanks for that!

That's the plan, man. 10.5" BA barrel's sitting here on my desk, and the receiver is in the safe. Trigger is in the mail. My can's in jail, but the pistol will be done when it's paroled. Done some conjugal visits with the 308, though. This is the beginning of a very looong and quiet relationship! Thoop, thoop... Hollywood, indeed!

So - to 98Z5V and all the rest, I'd like to report that opening up the gas port to 0.082" completely solved the issue. Function is now perfect - even with (crappy) M80 ball. Thank you all for your help! The next build is a 300 BLK, but the 308 is now in rotation!

Thank you, sir! I'll open it up, and let you know. It is a WC "Hunter" profile that's been discontinued. All the other specs are identical, (twist, etc.) to those you posted above. And I won't be using my bargain basement NATO ammo much any more, either. My hog and boar hunt that's coming up next month will be with actual 308s with 175gr SMK BTHPs. I suspect though, the gun will run just fine even with M80 ball after this surgery. Thanks again, pard!

Hey '98 - Don't mean to bother you, but have you any more words of wisdom on my gas port?

Perfect.

Time to buy a reamer! Thanks so much, '98!

Billymag -Much obliged. I suspect you are exactly right.

Much obliged. Just messaged him. BTW - I recommend Nomex, DNP.

Morning, guys. The gas port size is 0.070".

Right. I should be able to get within a few thousandths. Thanks, Doc. BTW - were you ever associated with the U of H? I did some consulting for the Optho Dept. there about 10 years ago. Designed an automated phoropter for them.

Yes I can. Let me get back to you tomorrow when I take the hand guard off and slide the gas block off the port. Is substantially smaller than the hole in the gas block. Love the Texas flag, BTW!

OK. So the locking lugs of the bolt have enough rearward travel to clear the bolt catch by about 1/4" before it reaches the limit. Seems that were the buffer any longer, it wouldn't clear at all, right? I understand that excess BCG speed can cause this problem, but it also seems like the gun is just barely running as it is. Wouldn't a heavier buffer, while certainly slowing down the BCG, result in even less travel? Examination of the buffer shows no evidence of contact with the end of the receiver extension. (Which is 7"). My next build is going to be a 6.5 CM, so your input is fantastic.

What I meant to say is that the BCG travel is substantially greater than sufficient for the mag follower to lift the bolt catch to lock the BCG open. Sorry if that wasn't clear. They, (WC), may also be doing a bit of ass covering. The barrel was dimpled, and it would take a much bigger idiot than me, (and that's saying something), to goof the installation of the gas block. I have removed it, and the carbon deposits are exactly concentric with the gas port on the barrel. Do you think that the combination of a 16" barrel with a 13.25" gas system might result in too short a dwell time, given the 3.8 oz buffer, and all the rest? WC is, in my experience, a pretty top-notch outfit. And the other components are from AP - perhaps not the most expensive, but certainly well regarded. It just seems that the physics of this 16" barrel with a 13.25" gas system is a bit marginal... And to all that have replied - thank y'all very much! Your hospitality here on this forum is really great!

Thanks! BTW the gas tube is also the correct unit from Wilson Combat. It is sort of a proprietary length and only available from them. I'll read the other stuff again.

So - great question. Yes it can be locked back by the charging handle, and the travel of the bolt is at least an inch past the point where the bolt catch clears the BCG. Thanks for your reply!

Good afternoon. I have just completed a 308 carbine build. It's an Aero M5 receiver set and an Aero BCG. The barrel is a 16" Wilson Combat Match, with a 13.25" "intermediate" gas system. The rifle cycles properly, but the bolt does not lock back on an empty mag. The buffer is DMPS spec 3.84 oz., and the spring is standard 31T. Using NATO M80 147gr FMJ ball. Ejection is at about 4:00. I also have an adjustable gas block that is wide open. When closed at all, the rifle does not feed or even eject reliably. It struck me that with this barrel and gas system length, the dwell time is pretty damn short. I contacted Wilson Combat, and they said the issue was likely restriction in my adjustable port, and I should change it to a fixed unit. Something about that just doesn't seem right to me. Comments would be much appreciated!