FSB's in 2020?

[opngrnd]

How dare you disparage set screw gas blocks in dimples by providing a first hand account of a failure.
You are supposed to anecdotally attack clamp on gas blocks.

Lol. Forgive me!

Yeah, my rifle shopped cycling and it took me a minute to figure out why. I mean, it couldn't possibly be the gas block, so why even look at it...but it was. And since it would shifted radially, as opposed to moving down the barrel, it was even harder to pick up on because the set screw was still providing tension. So it would clock side to side under recoil, sometimes being aligned, and when I first looked did not appear to be off. That particular barrel has 5190 rounds through it, which leads me to believe most people will never discover this problem if it can be a problem. It's off getting pinned right now.

[opngrnd]

You forgot to use high temp sleeve retainer when you installed the block. 🤣🤣 😝

Also remember to clean all oil off a steel gas block and barrel it will oxidize and hold tighter. Most set screw gas blocks come with too soft set screws. And yes I will not use them period: after going through all the process you end up with a gas block that is inferior to a pinned gas block.

True, but high temp sleeve retainer is not part of the equation that is usually recommended. You're average guy, including me, has been taught that red loctite is all you need...but I digress. I'm betting I somehow failed to properly prep the parts making the use of any adhesive at all semi-pointless, although cleaning parts is part of my build process.

[Five_Point_Five_Six]

I have had a gas block with knurled set screws and a dimpled barrel come loose before, despite using red loctite on the set screws. At this point, everything gets pinned, whether it's a low profile gas block or by using a FSB.

Well, red loctite is only good to 300 degrees so not surprising it gave way. 272 is good to like 450 degrees.

You can also stake the screws in place, like a castle nut it prevents them from working loose on their own but can still be removed with an allen wrench.

[Disciple]

You are supposed to anecdotally attack clamp on gas blocks.

That does seem funny to me. I have never seen set screws used to attach the stem of a hard use MTB. If clamp-on attachment is not secure enough set screw attachment surely isn't. But I like my pinned FSB.

[opngrnd]

Well, red loctite is only good to 300 degrees so not surprising it gave way. 272 is good to like 450 degrees.

You can also stake the screws in place, like a castle nut it prevents them from working loose on their own but can still be removed with an allen wrench.

What's your set screw staking method?

I also have considered to use rocksett going forward.

[1168]

What's your set screw staking method?

I also have considered to use rocksett going forward.

I use a starter punch to make four small stakes.

Loctite 2422 Medium Strength claims 650*. A tube will last a long time.

[opngrnd]

You forgot to use high temp sleeve retainer when you installed the block. ���� ��

Also remember to clean all oil off a steel gas block and barrel it will oxidize and hold tighter. Most set screw gas blocks come with too soft set screws. And yes I will not use them period: after going through all the process you end up with a gas block that is inferior to a pinned gas block.

Which sleeve retainer do you use?

Well, red loctite is only good to 300 degrees so not surprising it gave way. 272 is good to like 450 degrees.

You can also stake the screws in place, like a castle nut it prevents them from working loose on their own but can still be removed with an allen wrench.

Pictures! (Please.)

I use a starter punch to make four small stakes.

Loctite 2422 Medium Strength claims 650*. A tube will last a long time.

I'll order some. Could you post a picture of your staking?

Is there any reason we don't all use rocksett for this application?

[SteveL]

I have had a gas block with knurled set screws and a dimpled barrel come loose before, despite using red loctite on the set screws. At this point, everything gets pinned, whether it's a low profile gas block or by using a FSB.

I'm curious to know a little more about this. Was the gas block under a rail? And did it just spontaneously shoot loose?

[Five_Point_Five_Six]

What's your set screw staking method?

I also have considered to use rocksett going forward.

Spring loaded punch or a regular punch and a hammer. Rocksett will work, but will need to be soaked in water for days to free it up after prolonged use, at least in the experiences I have removing things secured with Rocksett.

Which sleeve retainer do you use?


Pictures! (Please.)


I'll order some. Could you post a picture of your staking?

Is there any reason we don't all use rocksett for this application?

I don't have any photos, and can't take any because the only uppers I have that don't have a FSB are MRP barrels and those are pressed and pinned in place.

[opngrnd]

I'm curious to know a little more about this. Was the gas block under a rail? And did it just spontaneously shoot loose?

Yes. And after checking my toolbox, they are correct in that my "red loctite" is only rated to 300 degrees...making it a matter of time until failure of the adhesive. I was sighting in a scope and my rifle stopped picking up new rounds (short stroking). I though it was the ammo, so I switched and it worked for a few rounds and resumed short stroking. Everything seemed fine. Then I tried a few more times and when I double checked the gas block it was slightly clocked. The set screw ended up being backed out enough to rotate but not so much it wasn't catching on the edge of the barrel's dimple. It had probably been loose for a short while before moving enough to induce a malfunction.