Undergassed DD 14.5 mid (URG-1 type)

[mack7.62]

Troubleshooting a build with a DD 14.5 mid gov that has a gas port of .075, cannot get consistent lock back with variety of ammo. Using Geissele gas block, BCM gas tube, Centurion C4 BCG, Vltor upper and A5H0 (started with H2). Ammo used Wolf Gold, Indy 13 (light case swipes), Federal .223, CBC M193 nothing is 100% reliable. Pretty disgusted with the whole thing, wonder if DD is gassing these barrels for M855A1, don't really want to drill out the gp but running out of ideas, any suggestions?

[Ajackz]

With everything you have said id recomend trying different magazines.

I think those DD barrels were tested to something like -40 degrees with H2 buffers with tue same gas port spec. You should be locking back with no issue if everything else is in spec and installed correctly.

Edit: also might be worth taking a look at the rings on your bolt.

[Aetius]

Have you tried swapping the BCG? Perhaps a loose carrier key, or to echo Ajackz, maybe rings

[vicious_cb]

I agree, sounds like a gas leak somewhere in the system.

[Jwknutson17]

That port size should run like a top with good ammo even with a sprinco blue and an H3 in a carbine system. Or an A5H2 and green. I chopped down a few of those barrels to 13.0 inches and they still ran with heavier buffers no problem. I would look elsewhere other then the port size as others suggested.

I would try doing the opposite of what your doing.... go heavier on the buffer. The A5H2 is a standard weight and your rifle should run an A5h4 with the cbc m193 without issue.

[Iraqgunz]

Something is off. IMPO .075 is a little small for a 14.5" mid. But it should be running as far as I know. You need to make sure to use a known quality mag with good ammo and do a lock back test. Load the magazine with 1 round and fire it. If it doesn't cycle and lock then you have an issue.

I would then swap out certain items like the BCG first. If it functions then I would narrow it down further to determine if it's the bolt or carrier. If that doesn't fix it, then you need to look at the block and tube. Also since you mentioned a DD barrel, has it been dimpled for the low profile gas block?

Troubleshooting a build with a DD 14.5 mid gov that has a gas port of .075, cannot get consistent lock back with variety of ammo. Using Geissele gas block, BCM gas tube, Centurion C4 BCG, Vltor upper and A5H0 (started with H2). Ammo used Wolf Gold, Indy 13 (light case swipes), Federal .223, CBC M193 nothing is 100% reliable. Pretty disgusted with the whole thing, wonder if DD is gassing these barrels for M855A1, don't really want to drill out the gp but running out of ideas, any suggestions?

[17K]

Those are off the shelf 14.5" mids. The barrel isn't your problem.

[vicious_cb]

Those are off the shelf 14.5" mids. The barrel isn't your problem.

Have you posted anything of late that isnt completely wrong?

OP stated this is a URG-I barrel made by DD. You know, the same company thats providing the exact same barrels to USASOC.

[17K]

Have you posted anything of late that isnt completely wrong?

OP stated this is a URG-I barrel made by DD. You know, the same company thats providing the exact same barrels to USASOC.

The URG-I uses a commercial off the shelf Daniel Defense 14.5" mid barrel.

[Todd.K]

That gas port size (if measured correctly) is smaller than I would expect a commercial 14.5" mid to be.

I wouldn't feel bad at all upping the port size a bit, but I would exhaust all troubleshooting first.