Adjustable Gas Blocks - Clamp vs Set Screw

Sniffer

Sniffer

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I'm trying to figure out what adjustable gas block I would like but I notice each is available in either clamp on or with a set screw.

Having never handled or used an adjustable whats the difference? Looking at them the clamp on is kinda self explanatory but it looks to me like the set screw variant is a set size and (I'm guessing) held in place with a set screw. If so I wonder how does it provide an adequate seal to the gas port and does the set screw back off long term (I imagine the clamp version to be more robust / hold better).

What is everyone using and why. I'm looking at Superlative Arms if that makes a difference but I am open to other brands if they are superior.
 
I have a Superlative Arms on my Stag10. I use the bleedoff setting on mine. I think the real benefit of the bleedoff is for suppressed guns. Not sure how how much the bleedoff setting effects a non-suppressed gun.
 
The primary function of the adjustable gas block for me is so I can pair it with a super light titanium BCG and tune for minimal recoil
 
I can imagine how the set screw setup works and how the clamp setup works but how does pinning work?

So if I want to pin do I purchase a clamp style / set screw style or is there a third style for pinning?
 
SA is great as is Odin adjustables.
Both clamp and set screw GBs are journal size specific. (0.625, 0.750, 0.936")
Generally I find the clamp on provides a better seal vs Set screw.
If there are no dimples on your barrel I think a clamp on stays in place better but neither will move easily.
There have also been cases on smaller sizes (0.625") where people have tightened the set screws too far and actually caused a deformation on the inside of their barrels, effectively ruining them.
 
scourge18a said:
SA is great as is Odin adjustables.
Both clamp and set screw GBs are journal size specific. (0.625, 0.750, 0.936")
Generally I find the clamp on provides a better seal vs Set screw.
If there are no dimples on your barrel I think a clamp on stays in place better but neither will move easily.
There have also been cases on smaller sizes (0.625") where people have tightened the set screws too far and actually caused a deformation on the inside of their barrels, effectively ruining them.
Click to expand...

Hmmm, I hadn't thought of that, I'm looking at a 0.875" barrel but something to be conscious of for sure. Clamp on is starting to sound more attractive.

So how is the dimple made? I imagine some kind of jig to ensure proper placement relative to the gas port and and a suitably sized drill bit?
 
Odin does both in .750, but only screw style in the larger 2 sizes. Big fan of the clamp on, but make sure your handguard will accept it, super skinny HG's are touch and go with any of the adjustable gas blocks. I had to go with a tunable form Odin works on a build to fit it the HG.

The tunable is adjustable, but after you get it adjusted you use a set screw to lock it in - and not adjustable again until you pull the set screw.
 
I’ve used both set screw(without dimples) and clamp on, on a Stag 10.
Never any issues.
I used a dab of blue locktite, just in case
 
Clamping (pinch style, not two piece) is more secure than set screws without dimpling the barrel. That said, I've used a number of set screw blocks without dimpling the barrel and never an issue. I don't generally concern myself with the attachment type.
 
Sniffer said:
I'm trying to figure out what adjustable gas block I would like but I notice each is available in either clamp on or with a set screw.

Having never handled or used an adjustable whats the difference? Looking at them the clamp on is kinda self explanatory but it looks to me like the set screw variant is a set size and (I'm guessing) held in place with a set screw. If so I wonder how does it provide an adequate seal to the gas port and does the set screw back off long term (I imagine the clamp version to be more robust / hold better).

What is everyone using and why. I'm looking at Superlative Arms if that makes a difference but I am open to other brands if they are superior.
Click to expand...

typically they are all machined to similar sliding fit tolerances, however the clamp style I imagine is better for sealing as it will distort the block to the diameter of the barrel. Actually pinches the barrel.

the set screw type if dimpled, and staked will withstand torsion better(It can rotate if no dimples), not really important as it will most likely be secured under a handguard, unlike a FSB.

I use a pinned and low pro gas block, came that way from KAC.

If you are going to use the set screw type, personally I would at the minimum dimple it for the set screws conical end to seat in. Others have told me they never dimple it, but I believe applying a force over the largest area is better than a single point (less distortion force on barrel). Set screw flats, grooves, and dimples you see in machine design is not a bad thing.
 
Pinned is always (almost always?) a set screw block that then has a cross pin drilled through the bottom of the barrel and driven in to make rotation impossible.
 
rommelrommel said:
Pinned is always (almost always?) a set screw block that then has a cross pin drilled through the bottom of the barrel and driven in to make rotation impossible.
Click to expand...

Thanks for the info.

I couldn't picture what pinned meant but your description makes perfect sense
 
I been looking into both types and noticed that the clamp on seem to be slightly bigger physically which could be an issue depending on what handguard I go with.

More research needed......
 
I have SA gas block in set screw and clamp. I prefer the set screw.

I dimpled the barrel myself by using knurled cup set screws to fix it in place and get it to function with the rifle. Once that was done I removed the knurled cup set screws and drilled 2 little dimples where the knurling was the same size of the cup on the SA set screws. Applied some red loctite and good to go.
 
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