Very specific question about Palmetto State Armory gas blocks

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flyboy015

New member
Howdy everyone! I have a pretty straightforward question: Regarding PSA's lightweight MLOK barreled uppers, is the gasblock that comes with those secured to the barrel with set screws or roll pins?

I'm helping a buddy spec out parts for an AR-15 build. He wants one very similar to mine (Magpul MOE SL handguard and no FSB). Trouble is, the barreled upper I bought a few years back for my rifle came with the A2 style FSB, and I had a hell of a time removing it due to the two roll pins. The two subsequent gas blocks I purchased (first non-adjustable, then upgraded to an adjustable GB) both were secured via setscrews.
 
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TrueBlue711

New member
If it's an MLOK barreled upper, then the gas block would be a low profile gas block to fit under the handguard. It's more than likely a set screw(s). I've never seen a low profile gas block use roll pins to attach to barrel.
 
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kymasabe

New member
I have a few PSA uppers with MLOK free float handguards and all those gas blocks are low profile with two set screws
 
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marine6680

New member
Most likely set screws.

Why does it matter though? If you like the handguard on the rifle then you won't have much need to remove the block.


The pins holding on the gas block are tapered, and therefore only come out in one direction, if you don't know that, it can make for a difficult time.


I don't know if they use red loctite on the set screws, and that can be a pain to get off. I know from experience... And keep in mind that a cheap or poor made bit will just be useless as well.
 
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Theohazard

New member
TrueBlue711 said:
I've never seen a low profile gas block use roll pins to attach to barrel.
Click to expand...
It’s very common to use a single roll pin through the bottom of a low-pro gas block to secure it to the barrel. Companies like AAC, Ballistic Advantage, and others sell barrels with pre-installed low-profile gas blocks secured with a roll pin.
 
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Theohazard

New member
To the OP: A low-profile gas block secured with a cross-pinned roll pin will be more secure than one secured with set screws. Unless you have an unusually-shaped gas block, any halfway-decent armorer or gunsmith should be able to drill and install a roll pin in your gas block even if it’s not designed for that.
 
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marine6680

New member
Dimples in the barrel for the set screws with high temp red loctite on them, that isn't going anywhere either.

Apparently early uppers coming out of Crane for the military, did that method, and they had no issues on combat.


BCM uses that method plus high temp retaining compound between the block and barrel. Retaining compound is designed to secure things like bearings to a round metal shaft... It is tough stuff, near impossible to break loose without a lot of heat. I know, I've used it before for work and other needs.

Requires so much heat, that I worry it would damage the barrel heat treat/temper if you removed it. A video I seen needed a high temp torch and over 30 seconds of direct heat to even get it to start moving.


But a roll pin is a simple and effective solution for a little extra retention above the set screws. Easier to deal with if you remove it later.
 
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