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Posted: 11/21/2012 5:52:18 AM EST
So I often see it written that pinned gas blocks are highly preferable to gas blocks that use set screws or some other retention device. While I completely understand the logic, I want to play devil's advocate and ask: has anyone actually experienced firsthand a quality non-pinned gas block coming loose, or heard about such an incident from a reliable source? We are also assuming of course that it was properly installed.

BTW, all my gas blocks are pinned. I'm just curious.
Link Posted: 11/21/2012 6:40:10 AM EST
I may be wrong, but doesn't the M4A1 sopmod block II include the daniel defense MK12 gas block which has set screws? If its good enough for the sopmod program, I would think that it's g2g for the most part.
Link Posted: 11/21/2012 6:43:34 AM EST
I have a Badger Ordnance Gas Block....Set Screwed...Dimpled barrel for one of the screws....accompanied with Loctite, have never had a problem.
Link Posted: 11/21/2012 6:48:23 AM EST
Even with the dimpled barrel, I would think that the heat would make the locktite useless. I am having this same question for my next build, and for my bcm build that Im installed a free float tube. I think with my current BCM upper that I will just convert the A2 Fsb to a low profile and make use of the existing holes drilled into the barrel for the pins.

Would rockset be more heat resistant?
Link Posted: 11/21/2012 6:56:09 AM EST
Rocksett is indeed more heat resistant. Stake the screw anyway.

I am indeed aware of instances of gas blocks coming loose.
Link Posted: 11/21/2012 7:04:03 AM EST
Not much to talk about:

pinned > clamp >> set screw
Link Posted: 11/21/2012 7:12:52 AM EST
I've always rolled with set screws. I have a White Oak barrel, dimpled twice, with set screws and red loctite. Gun has over 5K through it with no issues. YMMV.
Link Posted: 11/21/2012 7:25:31 AM EST
Just installed a DD low profile with two screws/clamp. Just used loctite, no dimples. Haven't shot it yet. Will have to test it out and check the screws after shooting it for the first time.
Link Posted: 11/21/2012 8:11:20 AM EST
Originally Posted By Combat_Jack:
Rocksett is indeed more heat resistant. Stake the screw anyway.

I am indeed aware of instances of gas blocks coming loose.




Have any pics of set screw staking?

Link Posted: 11/21/2012 8:15:36 AM EST
Originally Posted By evenflow:
Just installed a DD low profile with two screws/clamp. Just used loctite, no dimples. Haven't shot it yet. Will have to test it out and check the screws after shooting it for the first time.


How would a dimpled barrel help for a clamped on gas block?
Link Posted: 11/21/2012 8:19:11 AM EST

Originally Posted By Bizzarolibe:
So I often see it written that pinned gas blocks are highly preferable to gas blocks that use set screws or some other retention device. While I completely understand the logic, I want to play devil's advocate and ask: has anyone actually experienced firsthand a quality non-pinned gas block coming loose, or heard about such an incident from a reliable source? We are also assuming of course that it was properly installed.

BTW, all my gas blocks are pinned. I'm just curious.


milspec monekys did a "test" basically having to put a pipe wrench on it to turn the clamp on types.

If they are torqued correctly, they will be fine
Link Posted: 11/21/2012 8:20:01 AM EST

Originally Posted By Slu54:
Originally Posted By evenflow:
Just installed a DD low profile with two screws/clamp. Just used loctite, no dimples. Haven't shot it yet. Will have to test it out and check the screws after shooting it for the first time.


How would a dimpled barrel help for a clamped on gas block?
you dimple the barrel where the set screws contact, it allows them bite into the barrel and not just friction

Link Posted: 11/21/2012 8:21:38 AM EST

Originally Posted By Combat_Jack:
Rocksett is indeed more heat resistant. Stake the screw anyway.

I am indeed aware of instances of gas blocks coming loose.


breaking, or the screws backing out?

manf? Just normal use or was a sight other device on the gas block?
Link Posted: 11/21/2012 9:01:43 AM EST
Don't know all the details. Range use. Enough that I insist on pinning.
Link Posted: 11/21/2012 11:22:00 AM EST
I have a Midwest Industries low-pro gas block on my Recce. I torqued them to the specs in the directions it came with, used red Lock-tight and have never had a problem. I check the rifle over once a year. I check the Troy BUIS front and rear as well as the gas block set screws, never ever an issue OP. Simply mark the screws and a slight area around them with a white paint pen once torqued to the correct poundage. If the painted lines stay lined up... then your good to go. It's very easy to see if a screw is walking out using this method...
Link Posted: 11/21/2012 12:06:11 PM EST
Originally Posted By DDEL:
Originally Posted By Combat_Jack:
Rocksett is indeed more heat resistant. Stake the screw anyway.

I am indeed aware of instances of gas blocks coming loose.




Have any pics of set screw staking?



Nope. I only know one guy that does it.

He also staked a Short Dot into an SPR-E.
Link Posted: 11/21/2012 1:39:10 PM EST
How would a dimpled barrel help for a clamped on gas block?


There are two instances of "dimples" that would be relevant here. First, some barrels have a dimple on the bottom, directly opposite the gas port. Non-pinned gas blocks (either clamp-on or set screw type) may have a corresponding hole in the bottom. You just line up that hole with the barrel dimple and the gas port automatically lines up. Secondly, you could have dimples on the barrel where set screws bite. Those wouldn't apply to the clamp-on type.
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