Oversized gas port, but how much is an issue?

[ASH556]

I just received a new barrel for my carbine to replace the DD LW I had before. The barrel is a PSA CHF 14.7" - carbine gas. I measured the gas port in our machine shop @ work and was disappointed to find that it is .070. The Colt spec for a 14.5" carbine gas barrel is .063. So now that we know it's going to be over-gassed, the question is, how much. I'll be running it with a DD FA BCG and an H2 buffer. Should that make it ok? I'm a little more concerned that I would normally be because I have paperwork pending on an M4-2000 and if this gun is already going to be way over-gassed, the silencer will only make things worse.

Thoughts on "how" overgassed the gun will be? Likely to be an issue or not?

Thanks!

[patrick sweeney]

Build it and find out. Short of that, it is at best guesswork predicting what will happen.

[ASH556]

Build it and find out. Short of that, it is at best guesswork predicting what will happen.

Yeah, I know, but I guess my real question, is, "Is the 0.070 gas port large enough that the gun is going to be so overgassed that it's worth returning the barrel and waiting to find a Colt/BCM?" I have been looking/waiting for a couple weeks and jumped on the PSA when I found it. Most of what I've found talking about overgassed "commercial-grade" AR's from the likes of Bushmaster, RRA, ETC puts the gas port in the .083 range. I'm not that bad off. Just wondering how much of a difference .007 makes in reality.

[Magic_Salad0892]

Yeah, I know, but I guess my real question, is, "Is the 0.070 gas port large enough that the gun is going to be so overgassed that it's worth returning the barrel and waiting to find a Colt/BCM?" I have been looking/waiting for a couple weeks and jumped on the PSA when I found it. Most of what I've found talking about overgassed "commercial-grade" AR's from the likes of Bushmaster, RRA, ETC puts the gas port in the .083 range. I'm not that bad off. Just wondering how much of a difference .007 makes in reality.

As long as you're not shooting suppressed, you can probably throw in a Sprinco Blue, and an H2 and be good.

But I'd still prefer an .063'' port.

[markm]

My 14.5 runs good at .063 with no can. It's functional with the can but it's flinging the brass forward.

In all actuality, I ran that turd for years before I put an insertable port into the FSB and choked it down to .063.... and it worked ok with an H3 buffer.

With a silencer, there's no question it's going to have TOO MUCH gas. But possibly not so much that an H3 buffer can't help.

If you plan to run the can most of the time... I'd look at restricting that gas flow a bit. Properly gassed guns just run SO MUCH smoother.

[patrick sweeney]

.070" is 23% larger an orifice than .063" but that doesn't mean 23% more gas.

Run it and try it. If it proves to be too much, even with an H3, you can always throttle it down. Or put on a switchable gas block.

[markm]

Or put on a switchable gas block.

The problem with a switchable is you give up the FSB and then most likely have to reconfig the handguard.

It's a good option if you're wanting a lo pro gas block anyway.

[ASH556]

Yeah, the gas block will be under a 12.5" DD RIS II rail, so no switchable. I guess I'll throw it together and hope it works. Good thing I have an SBR lower to run it on so I don' have the FH pinned only to find out I have gas issues.

[markm]

Yeah, the gas block will be under a 12.5" DD RIS II rail, so no switchable. I guess I'll throw it together and hope it works. Good thing I have an SBR lower to run it on so I don' have the FH pinned only to find out I have gas issues.

Oh for Christ's Sake. Get the SYRAC. It has long wrenches that can adjust from the front like 5 or 6 inches under the rail. I have one on my shelf that I haven't got to install yet... But i've played with the adjustment system. It's solid.

Slam Dunk. I thought you were keeping the FSB.

[Magic_Salad0892]

Yeah, the gas block will be under a 12.5" DD RIS II rail, so no switchable. I guess I'll throw it together and hope it works. Good thing I have an SBR lower to run it on so I don' have the FH pinned only to find out I have gas issues.

SYRAC will fit under a rail.