Very specific question about Palmetto State Armory gas blocks

flyboy015 · July 10, 2018, 08:25 AM

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.

TrueBlue711 · July 10, 2018, 08:55 AM

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.

kymasabe · July 10, 2018, 12:05 PM

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

marine6680 · July 10, 2018, 04:36 PM

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.

bfoosh006 · July 18, 2018, 04:53 PM

Set screws... I have yet to see a GB pinned from PSA.

imashooter · July 18, 2018, 06:27 PM

I have 2-3 PSAs and they're set screwed. Work just fine without dimples.

Theohazard · July 19, 2018, 08:00 PM

Quote:

Originally Posted by TrueBlue711

I've never seen a low profile gas block use roll pins to attach to barrel.

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.

Theohazard · July 19, 2018, 08:19 PM

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.

marine6680 · July 20, 2018, 01:18 AM

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.

July 10, 2018, 08:25 AM	#1
flyboy015 Member Join Date: June 2, 2016 Location: Pennsylvania Posts: 77	Very specific question about Palmetto State Armory gas blocks 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.

July 10, 2018, 12:05 PM	#3
kymasabe Senior Member Join Date: June 10, 2005 Location: SW Florida Posts: 2,747	I have a few PSA uppers with MLOK free float handguards and all those gas blocks are low profile with two set screws __________________ God's creatures big and small, eat them one, eat them all.

July 19, 2018, 08:19 PM	#8
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	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. __________________ 0331: "Accuracy by volume." Last edited by Theohazard; July 19, 2018 at 08:45 PM.

July 10, 2018, 08:55 AM	#2
TrueBlue711 Senior Member Join Date: March 16, 2011 Posts: 489	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.

July 10, 2018, 04:36 PM	#4
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	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.

July 18, 2018, 04:53 PM	#5
bfoosh006 Senior Member Join Date: February 17, 2009 Posts: 1,089	Set screws... I have yet to see a GB pinned from PSA.

July 18, 2018, 06:27 PM	#6
imashooter Senior Member Join Date: December 28, 2013 Location: Alabama Posts: 395	I have 2-3 PSAs and they're set screwed. Work just fine without dimples.

July 20, 2018, 01:18 AM	#9
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	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.