What type of pin do I need to a gas block?

[Wow]

Hello,
I am in the process of building a upper. I have a criterion barrel and vltor gas block that uses set screws. I want to have the gas block pinned for increased reliability.

I need helping figuring out what pin to buy to pin the gas block the the barrel. My vltor gas block only came with a pin for the tube.

So far I have gotten to 1/8 x 5/8 but 5/8 seems kinda long for a 0.625 gas block.

What do you think? What pin are you using in a .625?

https://i.imgur.com/hd9av1E.png

[grizzman]

I would let the company that will be performing the work make that decision. I'm certain they will happily sell you the appropriate pin as part of the work package.

[Wow]

You are underestimating the amount of half-assing gun smiths in the world.

[grizzman]

Actually, I'm not. There are only three companies in my metropolitan area that I'd trust to do any smithing beyond what I'm capable of completing. I've personally used ADCO, and was completely satisfied with their work, price, and the time it took for them to complete the work.

Here's a thread from a few years ago that seems rather familiar.https://www.m4carbine.net/showthread...-and-gas-block

This topic has come up several times since the linked thread, and Marvin Pitts, Retro Arms Works, and ADCO are pretty much always recommended.

[Wow]

Reading that thread has made me decide to not even pin it. I got a criterion barrel and I trust their opinions. Guess I should look into high temp thread locker. Weird though that they only dimple one of the set screw places on their barrels.

[markm]

Reading that thread has made me decide to not even pin it.

Good call!!

[sniperfrog]

Reading that thread has made me decide to not even pin it. I got a criterion barrel and I trust their opinions. Guess I should look into high temp thread locker. Weird though that they only dimple one of the set screw places on their barrels.

I wouldn’t use high temp thread locker. If you ever decide to take the upper apart you wont ever get the screws out. Rockset is water soluble but that’s only if the water can get to the threads. I had to drill out some set screws I used Rockset on.
I believe some people just use blue loctite which isn’t high temp rated but still helps keep the threads from backing out. I use knurled cup set screws and haven’t had any back out.

[titsonritz]

I wouldn’t use high temp thread locker. If you ever decide to take the upper apart you wont ever get the screws out. Rockset is water soluble but that’s only if the water can get to the threads. I had to drill out some set screws I used Rockset on.
I believe some people just use blue loctite which isn’t high temp rated but still helps keep the threads from backing out. I use knurled cup set screws and haven’t had any back out.

BCM, SIONICS and SOLGW all use red loctite along with knurled set screws on their LPGB. Red requires a torch or similar to break its grip.

ETA:
Go to minute mark 2:33...

[HKGuns]

Yeah I use Hot Lock and don’t pin them.

It isn’t very difficult to heat up those minuscule fasteners.

[grizzman]

I certainly wouldn't go through the effort to pin a gas block, especially if it's going to be under a free float handguard.

It sure would be nice if all gas block manufacturers used the same set screw spacing. If they did, then the barrel manufacturers could cut two dimples, and know they're in the right locations.
I personally standardized on one spacing, and bought the dimple jig for it. Jgs are now available for a variety of different spacings in the same jig.

It's not difficult at all to heat up Loctite 272 enough to allow for removal of the set screws.....just don't put too much force on the tiny set screw until the locker has been disabled.