Clamp vs Set Screw gas block
- Thread starter Vwork
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Either work just fine. Some prefer one over the other. I have both and used both heavily. They both work just fine
On a DI it doesn’t really matter, I feel like solids are easier to line up the gas ports but whatever floats your boat. on a piston I much prefer the solid with a properly dimpled barrel.
I read once that the set screws could "wreck accuracy." The block on my RRA predator pursuit had set screws, and it shot sub 3/4 moa. I aways by clamp on as a result of one stupid thing I read, that may not be true.
I have plenty of both, the only notable difference is that the set screw type gives you more clearance in a small ID handguard.
I read the same thing years ago and it made sense at the time but hasn’t played out to be true in my experience. YRMV
I have used both on steel barrels. But don't think that I would really want to dimple a Proof carbon barrel, so would opt for the clamp-on verses the set-screw.
I had to look at what you're working with because I have not seen one of these barrels. This is what I found:
So based on this you won't be dimpling the carbon fiber. However, you will need to be more careful setting up the barrel to do the dimples if you choose to use set screws. Some prefer this type because there is less chance for the gas block to slide toward the muzzle as the set screws in the dimples will prevent that. If you get the dimple in the wrong location the gas block will try and migrate in the direction of the center of the dimple and changing the dimple location can be tricky as the drill will try and do the same. This is why some prefer the clamp on version, easier to readjust if needed and no need to drill dimples in the bottom of the barrel.
So based on this you won't be dimpling the carbon fiber. However, you will need to be more careful setting up the barrel to do the dimples if you choose to use set screws. Some prefer this type because there is less chance for the gas block to slide toward the muzzle as the set screws in the dimples will prevent that. If you get the dimple in the wrong location the gas block will try and migrate in the direction of the center of the dimple and changing the dimple location can be tricky as the drill will try and do the same. This is why some prefer the clamp on version, easier to readjust if needed and no need to drill dimples in the bottom of the barrel.
Read the same thing about set screws and accuracy...only reason I use clamp on as well. May be a myth but I have no proof nor reasons to change.
...used both and have since preferred to use the clamp type. Reason: Better gas journal seal with clamp type. Barrel gas journals will differ in OD dimensions just as gas blocks will differ in ID dimensions. The clamp type can accommodate those differences better, providing a better seal from the get go. Caveat: Gas leakage will eventually accumulate and build up into a seal with set screw type as well, but it can be disconcerting when you see that initial leakage evident on a new assembly. When you have minimal effort required (loose fitting) when you slip the gas block over the barrel gas journal, that indicates a dimension mismatch. As you tighten the set screws the gas block upper section is "pulled down" for a closer fit, but the lower half is "pulled away" and increases the gap between the outer portion of the gas journal and the inner portion of the gas block.
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The issue some are reporting with a set screw affecting accuracy would be related to inexperienced builders tightening the shit out the set screw creating a pressure point in the barrel.
Properly tightened there is no issue and either work fine just choose which one you prefer.
Properly tightened there is no issue and either work fine just choose which one you prefer.
This, plus you have more clamping force with a clamp on vs set screw. I've also had pre dimpled barrels work against me for set screw positioning. I buy nothing but clamp on now.
1.) you wouldn’t be dimpling the carbon fiber. The gas block location is all stainless. I mean, really? Is that not obvious from the pictures!?!
2.) my Proof Carbon Fiber wrapped barrel came dimpled for a set screw gas block. I put a Ti SLR set screw block on it because I’m running a 15” KMR A. Works great. Clears great. SLR sends instructions on what to torque the set screw to in in/lb. I rocksett the set screw and beddedthe block w/rocksett.
2.) my Proof Carbon Fiber wrapped barrel came dimpled for a set screw gas block. I put a Ti SLR set screw block on it because I’m running a 15” KMR A. Works great. Clears great. SLR sends instructions on what to torque the set screw to in in/lb. I rocksett the set screw and beddedthe block w/rocksett.
I've used JP Enterprises and Superlative Arms clamp-on gas blocks and have never had a single issue with them on any of my builds. The only thing that I learned is not to use Loctite on the screws in the gas block. Rocksett is apparently the way to go for gas blocks since it is unaffected by heat. I've used Rocksett on 3 builds and over years of shooting thousands of rounds they've been reliable.
I like the idea of clamp on because I feel it allows for a tighter fit and also seems less likely to loosen once properly torqued, BUT they typically don't fit under the slim handguards so popular today. I'm pretty much stuck with set screw since my handguards require it. I've never had a problem with either coming loose.
I'm sure everyone has their own settings they like to use but I think the general consensus is 15-20 in-lbs (wet) when torquing set screws (if you don't use threadlocker I'd prob bump it up slightly to 20-25 or something). For clamp on blocks I torque them a little more to around 30 in-lbs.
For threadlocker I've settled on permatex orange 25210 (can handle high temps and doesn't need high heat to remove like loctite 272). You could also use a loctite like 246 or something if you want to avoid 272. Rocksett also would work.
If you plan on tinkering around with the build a lot I would avoid 272 or threadlocker and just put a little oil on the threads, torque to 15-20 in-lbs and test your rig. Once it passes function checks, etc. then I add permatex orange threadlocker to the screws and witness marks with paint pen whether its set screw or clamp on style.
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You torque set screws? LOL.
Here is a little secret. Fastener torque envelopes can be felt with an allen key of the appropriate size. Once the long arm starts to bend, you are as tight as you need to be. More ugah = stripped head and less ugah = come loosey. If its that important to have exact torque, its getting saftey wired and withness marked anyway, with the fastner being shitcanned after once cycle.
Pinned is the most reliable followed by Dimpled set screws. The main cause of gas block failure is rotation and obstructing the gas port. Clamped blocks are 100 times more likely to have this happened than mechanically pinned and set block. You can use a clamp if that is the only option but I don't use them and wouldn't any any gun i have sold or will sell.. Either pinned or I will drill the barrel for set screws with the shit loctighted out of them. The Gas block will fail( internal mechanical) , the barrel will be toast and the gas port will be eroded like a wizzards sleeve before the block moves on the barrel.
Here is a little secret. Fastener torque envelopes can be felt with an allen key of the appropriate size. Once the long arm starts to bend, you are as tight as you need to be. More ugah = stripped head and less ugah = come loosey. If its that important to have exact torque, its getting saftey wired and withness marked anyway, with the fastner being shitcanned after once cycle.
Pinned is the most reliable followed by Dimpled set screws. The main cause of gas block failure is rotation and obstructing the gas port. Clamped blocks are 100 times more likely to have this happened than mechanically pinned and set block. You can use a clamp if that is the only option but I don't use them and wouldn't any any gun i have sold or will sell.. Either pinned or I will drill the barrel for set screws with the shit loctighted out of them. The Gas block will fail( internal mechanical) , the barrel will be toast and the gas port will be eroded like a wizzards sleeve before the block moves on the barrel.
Haha, I don't really use a torque wrench on set screws anymore and use feel/bend on the arm as you described, but if someone has no idea what it should feel like the torque wrench can give them an idea and once they do it enough times they won't need it. I definitely also witness mark the screw heads regardless of set screw or clamp on.
There was a time that I only used clamp ons because of a belief that set screws could mess up accuracy. Then I had it in my head that clamp ons could affect accuracy by squeezing the barrel.
Now, I just use knurled cup point set screws tightened to where the Allen key starts to bend and I dont go nuts with the torque on clamp ons. They both do they job. I do, however, prefer a clamp on gas block if it serves as a front sight mount.
Now, I just use knurled cup point set screws tightened to where the Allen key starts to bend and I dont go nuts with the torque on clamp ons. They both do they job. I do, however, prefer a clamp on gas block if it serves as a front sight mount.
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