Anyone ever had this happen?

[gasrat]

So a few weeks ago, I put together a 10.5 pistol. .750 barrel and installed a YHM gas block. Everything went together fine. Decided I wanted to use the upper on a 20" build, so I took the pistol back apart. Gas block came off the barrel fine. Now, I have got the pistol back on another upper, but the YHM machine gas block will not go back on the 10.5 barrel I removed it from. I called YHM and they are as confused as I am.

I initially thought when I tightened up the gas block, it squeezed the block together for a tighter fit. But there was nothing like that felt when removing it, and it slid off the barrel fine. The block will clear the first couple inches of the barrel from the muzzle, but where the barrel steps up to .750, the damn block will not go any further. Anyone else ever run into this?

 

[Jgault]

I’ve had gas blocks that did similar things due to carbon build up, it has to be either that or the block wings bent in when you installed it the first time, I don’t see a third possibility. I would dole it in solvent and scrub just to see assuming you had fired it before taking it apart the first time.

 

[Gohring65]

Lube it up and hammer it home. If it came off of it, it’ll go back on.

 

[UpSideDown]

Clean the outside of the barrel gas journal and the inside of the gas block, they probably have carbon buildup on them that's causing it to hang up. Clean them just like a dirty barrel. Don't use anything abrasive.

 

[supercorndogs]

Is it the split clamp style? If so remove the screws, put a small piece of metal in the slot on the bottom, start the screws in the wrong side, and use them with the metal inserted to spread the gas block open ever so slightly. {Just enough to slide on, then you can remove the screws and metal, and re-install the screws on the correct side.}

 

[Lange Carabine]

Is it the split clamp style? If so remove the screws, put a small piece of metal in the slot on the bottom, start the screws in the wrong side, and use them with the metal inserted to spread the gas block open.

Was about to suggest the same exact thing, you beat me to it.

 

[Mike_in_FL]

I'd measure that new barrel to make sure it's .750 where it should be also.