Gunsmithing JP adjustable gas block screwup. Help needed!

[Jimlaw83]

So my Form 4 gets back this week, and in anticipation of that I bought a JP adjustable block for my heavy barrel AR. Taking from the other thread here about adding a set screw (I intend to shoot varmint and target loads suppressed and unsuppressed), I bought a 6-32 tap. I drilled from the top of the block just like shown, and the hole matched up fine with the pre-drilled adjustment screw hole. Like an idiot, however, I didn't think I needed a bottom tap, and ended up going clean through the adjustment screw hole! In essence, I ended up creating an extra gas tube port hole right next to the actual one.

Any ideas on how I can fix this? My thought was to putty the gas port hole on the block, and put a dab of jb weld in my newly created hole to seal it back up. I'm up for any ideas y'all may have for help. Or if the block is just kaput, that's fine too.

 

[Jimlaw83]

Re: JP adjustable gas block screwup. Help needed!

I'll see if I can get pics tonight and post them to help with visualization as well.

 

[BigBlue&Goldie]

Re: JP adjustable gas block screwup. Help needed!

Can you plug it with another set screw?

 

[RADcustom]

Re: JP adjustable gas block screwup. Help needed!

JB weld will probably soften from the heat. A plug screw and rockset would last longer.

 

[Jimlaw83]

Re: JP adjustable gas block screwup. Help needed!

Thanks for the responses guys. Wish I had gotten a pic, hope this description is better.

My accidental hole is on the inside surface of the block next to the gas tube hole, i.e. is in contact with barrel. If I put a plug screw in, I believe that will block the adjustment screw hole.

Sorry I didn't get any pics to help see, got my suppressor in and had to play kid at Christmas. But the accidental hole is at a right angle vertically and horizontally to the factory adjustment screw hole. The adjustment screw hole enters in the side of the block and goes across the top of the barrel at a 90 degree angle, across the gas tube hole. The set screw hole I drilled comes down from the top of the gas block vertically and intersects the adjustment screw in between the gas tube and rifle right side of the gas block. If i had drilled while block was on rifle, i would have wnded up going down into the barrel. Make sense? I really need to get a pic tonight to show.

 

[Jimlaw83]

Re: JP adjustable gas block screwup. Help needed!

I would think welding would be best option, lol sadly I don't know anyone with a welder. Over a $79 part, may just buy a new one. Really wish Noveske made a switchblock for heavy barrels. (.936)

 

[turbo54]

Re: JP adjustable gas block screwup. Help needed!

If the setscrew plug won't work, I'd try the JB weld. NOT JB-Quick, but rather, JB WELD....that is, if this is just a range toy and your life (or match score) won't be destroyed because the rifle craps out.

JB Weld is rated to 600ºF, and I've used it in some "high heat" applications with great success.

An example:

I used to play a lot with Ford 2.3 turbo engines. I never liked the OEM exhaust manifold because its openings were actually smaller than the exhaust ports in the head. The way Ford positioned the manifold bolt holes in the head, there was just no way to make a header with a big enough opening - so I redrilled the bolt holes in new locations. Half of the holes went into the water jackets.

Well, I didn't get any extra power out of the new header, and someone offered me $1500 for it, so I decided to switch back to the original manifold...meaning I had to plug the new holes in the head that went through to water. Worse yet, the manifold would actually partly cover those holes.

I cleaned up the holes with scotchbrite/acetone, sandblasted some set screws, and JB welded them in place. Because the manifold was literally going to be resting against them, and that manifold glows bright red under load, I figured this "fix" wouldn't be long for this world. But in fact, it lasted 50,000 miles until I sold the car (yes, I informed the buyer about what I'd done), and as far as I know, never failed.

Some key points on this "fix":

1. One side of the setscrew is in direct communication with watert that is never hotter than 215ºF
2. The other side of the setscrew is in direct communication with a piece of iron that reaches 1600ºF

JB Weld is a thermoset polymer, so it isn't going to "soften". It will harden further and flake off when it fails from heat.