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Posted: 2/27/2021 5:02:10 PM EDT
[#1]
Depending on the gas block, you may have trouble finding a clamp on. I've been struggling with the lack of available stock and might be buying a set screw block to get what I want in the size I need for my handguards. I feel like in general, clamp on makes a better seal.
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Posted: 2/27/2021 5:45:47 PM EDT
[#2]
clamp is big lame trash, dimple it.
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Posted: 2/27/2021 5:57:45 PM EDT
[#3]
Quote HistoryQuoted: clamp is big lame trash, dimple it. 
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Posted: 2/27/2021 6:17:12 PM EDT
[#4]
Quote HistoryQuoted: Well Im right, between the 2 options dimple is far superior and to make it better you pin it. EABOD |
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Posted: 2/27/2021 6:40:48 PM EDT
[#5]
In the time that it took to post this thread and read responses you could have dimpled your bbl.
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Posted: 2/27/2021 8:17:56 PM EDT
[#6]
Quote HistoryQuoted: Well Im right, between the 2 options dimple is far superior and to make it better you pin it. EABOD Quote HistoryQuoted: Quoted: Well Im right, between the 2 options dimple is far superior and to make it better you pin it. EABOD No, clamp on is just as secure when properly installed and causes less point stresses in the barrel. |
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Posted: 2/27/2021 10:09:47 PM EDT
[#7]
I only use clamp-on blocks for my accuracy builds - the stress induced by set screws or pinning will distort the barrels that I paid good money for. A clamp-on gas block distributes the force evenly so distortion is minimized. If you're working with a rack-grade barrel, it won't matter. I use EGW blocks on my spaceguns. I also find that a clamp-on block is much easier to remove when I rebuild a rifle - a block that is pinned or dimpled gets very thoroughly glued in place by powder residue.
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Posted: 2/27/2021 10:14:05 PM EDT
[#8]
Quote HistoryQuoted: Well Im right, between the 2 options dimple is far superior and to make it better you pin it. EABOD Quote HistoryQuoted: Quoted: Well Im right, between the 2 options dimple is far superior and to make it better you pin it. EABOD Dude, you are painfully incorrect. I'd put my Vltor clamp-on against any of your set screw. |
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Posted: 2/27/2021 11:14:08 PM EDT
[#9]
You don't need to dimple a barrel to use a set screw GB.
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Posted: 2/27/2021 11:41:49 PM EDT
[#10]
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Posted: 2/28/2021 12:13:09 AM EDT
[#11]
I prefer one single dimple (breach end). The breach end set screw is the only one that will be consistent with all gas blocks. It is always aligned with the gas port and gas passage of the gas block, ensuring proper alignment and set back from the barrel shoulder. There are 5 common and a number of less common set screw spacing dimensions. If you dimple the forward set screw, make sure your jig has the same spacing as your gas block. One of the more irritating scenarios is when the forward dimple is misaligned by ~1/2 the diameter of the set screw.
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Posted: 2/28/2021 11:52:55 AM EDT
[#12]
Quote HistoryQuoted: clamp is big lame trash, dimple it. manufactures got it wrong. you ought to design a rail that attaches via two set screws instead of clamping a barrel nut since this method is obviously superior |
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Posted: 2/28/2021 12:22:08 PM EDT
[#13]
Clamp ON, Clamp OFF, the Clamper!
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Posted: 2/28/2021 12:47:24 PM EDT
[#14]
I haven't went into battle with clamp on or set screw gas blocks so I won't claim to be an expert on what's better. I'd guess that a clamp on would have more chance of spinning out of position if it was whacked but that would only be an issue if the block was exposed (not under a rail). A clamp on has more surface area against the barrel, so it has an advantage in that regard. A clamp on installed with Permatex would seem pretty bomb proof, although I have no experience with a clamp on. I would only trust a set screw block if the barrel was dimpled and the screws were Loctited, this is what I've done and had no issues. If the gas block is under a rail, I think either should be reliable as long as they're installed correctly.
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Posted: 2/28/2021 1:01:03 PM EDT
[#15]
I got both!
 Used a KAK drill jig to dimple a Faxon barrel for a retro fsb with set screw and it was crooked. Went clamp on to remedy. It looked straight until the fsb went on but I just eyeballed it and figured it would be right. Wrong. |
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Posted: 2/28/2021 9:45:46 PM EDT
[#16]
Not sure what someone has against clamp on but if you think that clamp on can slip over time you are mistaken. We used clamp on shaft couplings on high horse power motors for industrial equipment with never a problem. That is, clamp on only, no keys.
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Posted: 3/1/2021 3:53:54 PM EDT
[#17]
Quote HistoryQuoted: You don't need to dimple a barrel to use a set screw GB. My observations with GB's: 1) Without a dimple I would prefer one set screw be made of high carbon tool steel with a nice point on it so it can dig in just a smidge to help keep GB from rotating. The only possible issue with this is, if the point pushes up a smidge of bbl metal (when point makes the crater) this can make it difficult to remove the GB later. 2) One dimple should suffice, not sure what two dimples get you. 3) Less any super high precision rifle stuff (although I have not seen any data myself that suggests a little set screw will throw off the accuracy/precision of the setup), dimple or clamp-on will suffice, and in many cases no-dimple at all will be ok. 4) I don't care who made the jig or block or barrel, unless all three were made as a DIY matched set, I always mic/gauge things to make sure the GB will be in the correct position when attached. How you mic/gauge it is up to you, but I have the tools to check it all. One or all three items may be off. 5) The KAW Valley dimple jig is fairly nice. I am not sure if all jigs allow you to eyeball the gas port but the KV jig does. I will use a pin gauge to "center" the jig to the bbl gas port before drilling the dimple(s). 6) Clamp-on GB's come many ways, 2screw, 3screw, 4screw. The more screws the more clamp force the GB can have. But for the OP - if using a clamp-on is the easier way, then use a clamp on. The challenge is always making sure the GB port and bbl port are properly aligned. Some GB's have a line scribed on them for alignment, but not all bbl's do (you can add a line though), and even with that the port offset from shoulder may be off (hence why I mic/gauge things to see how good or bad the machining was). |
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Posted: 3/1/2021 6:35:28 PM EDT
[#18]
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Posted: 3/1/2021 8:25:15 PM EDT
[#19]
Ranked best to worst in my opinion
1: Pinned gas block 2: Dimpled barrel, staked screws 3: Dimpled barrel, rock-set screws 4: Dimpled barrel and tightened screws 5: No dimples, Screws only (Clamp on blocks vary in design and usage. I won’t speak on the durability of something I don’t own or use often) 1-2 are proven methods/safest 3 would suffice for duty use depending on conditions 4-5 is fine for plinking With no access to a dimple jig, the edge of a file will work in creating a groove or flat spot for the set screw to contact. Locktite is not really a reliable option when high levels of heat are involved. “Plinking” would probably be fine with red locktite Staked screws on gas block:  Attached File***Not my picture. I prefer to do mine from the side similar to a gas key*** |
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Posted: 3/1/2021 9:04:56 PM EDT
[#20]
Quote HistoryQuoted: Locktite is not really a reliable option when high levels of heat are involved. “Plinking” would probably be fine with red locktite .Mil armorers/TM would disagree .  Attached FileThis is the correct way. |
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Posted: 3/1/2021 11:35:31 PM EDT
[#21]
Quote HistoryQuoted: .Mil armorers/TM would disagree . https://www.ar15.com/media/mediaFiles/416992/Screenshot_20210301-190104_Photos_jpg-1847365.JPG This is the correct way. Quote HistoryQuoted: Quoted: Locktite is not really a reliable option when high levels of heat are involved. “Plinking” would probably be fine with red locktite .Mil armorers/TM would disagree . https://www.ar15.com/media/mediaFiles/416992/Screenshot_20210301-190104_Photos_jpg-1847365.JPG This is the correct way. Mil armourer = clerk that keeps track of paperwork TM = The military version of a shitty instruction manual You should have just whipped out a dusty MK12 TM from the beginning and stopped this entire conversation from taking place. In all seriousness, just because the military teaches poor doctrine doesn’t mean we should perpetuate it in the civilian sector. Here are my credentials, I guess it makes me a badass on this forum:  Attached FileI don’t even think my CPT knew how to spell armorer, so he wrote armor instead. P.S. To all the non-military guys: Don't ever let someone lead you to believe that average military training, doctrine, or technical manuals in any subject is somehow superior to anything, especially if there is a civilian counterpart. I’ll bust out some more memos and certs though if it gives Tig a warm and fuzzy feeling. I’ll face palm myself if someone mentions infosec. |
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Posted: 3/2/2021 1:24:59 AM EDT
[#22]
Quote HistoryQuoted: Best type of set screw for GBs: https://www.ar15.com/media/mediaFiles/416992/unnamed_jpg-1847165.JPG Add some red Loctite and worry not. You didn’t follow the MK12 TM by the way. It says blue locktite https://www.ar15.com/media/mediaFiles/416992/Screenshot_20210301-190104_Photos_jpg-1847365.JPG 
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Posted: 3/2/2021 6:46:00 AM EDT
[#23]
Quote HistoryQuoted: Mil armourer = clerk that keeps track of paperwork TM = The military version of a shitty instruction manual You should have just whipped out a dusty MK12 TM from the beginning and stopped this entire conversation from taking place. In all seriousness, just because the military teaches poor doctrine doesn’t mean we should perpetuate it in the civilian sector. Here are my credentials, I guess it makes me a badass on this forum: https://www.ar15.com/media/mediaFiles/496867/32FD50F1-9FC0-4762-AFCD-E90041B23BFA_jpe-1847594.JPG I don’t even think my CPT knew how to spell armorer, so he wrote armor instead. P.S. To all the non-military guys: Don't ever let someone lead you to believe that average military training, doctrine, or technical manuals in any subject is somehow superior to anything, especially if there is a civilian counterpart. I’ll bust out some more memos and certs though if it gives Tig a warm and fuzzy feeling. I’ll face palm myself if someone mentions infosec. All well/fine, but I find it odd that a handful of armorers working with SOCOM guns daily report that that the MK18s /M4A1s hold up fine using Loctite and are not shitting out set screws. As for "warm/fuzzy"....it's not why I come here. |
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Posted: 3/2/2021 6:47:32 AM EDT
[#24]
Quote HistoryQuoted: You didn’t follow the MK12 TM by the way. It says blue locktite https://www.ar15.com/media/mediaFiles/416992/Screenshot_20210301-190104_Photos_jpg-1847365.JPG My guns, my way. Always been that way, always will. 
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Posted: 3/2/2021 8:31:27 AM EDT
[#25]
Any tests ever been done comparing the various methods?
Pinned, set screw, clamped, and other? |
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Posted: 3/2/2021 9:57:53 AM EDT
[#26]
Quote HistoryQuoted: Any tests ever been done comparing the various methods? Pinned, set screw, clamped, and other? That's a good question. I know everyone has a preference but in reality, most "red" loctite has the same heat resistance as the blue ones. There are numerous different specific formulas but all of the common blue and red loctite are good to ~300 degrees. The high temp red is the odd ball at I think 700ish degrees. The real difference is torque to break it loose once set. I believe medium weight blue still requires like 75 lbs to move it once set. Note, this is largely from memory so those numbers could be off but the idea is sound. I'd love to see some real world comparisons of the various attachment methods and preferences and see how they stack up. My guess is none of them are so bad that they are completely unusable, though, I bet a clamp on is better that an undimpled set screw. That said, i would also guess an undimpled set screw will probably perform better than most people will push their rifle to need. |
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Posted: 3/2/2021 11:04:39 AM EDT
[#27]
I can’t take anyone seriously who’s process of assembling a rifle is to see how little they can get away with or how many shortcuts can be taken.
If you don’t understand how to do it yourself or don’t possess the tools, there is no shame in paying a professional to assemble your rifle or buying a factory built upper/lower. Who is more respectable? The novice who has identified his own lack of knowledge or the novice who thinks he has nothing left to learn? |
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Posted: 3/2/2021 11:26:21 AM EDT
[#28]
My biggest problem with the dimple and set screw is the execution of the process. If dimpled in a Bridgeport mill with a clampable v-block and a precise method of finding bottom dead center of the barrel is performed the results are great. (Like it would be performed by a experienced gunsmith) You must also start with a center drill and progressively work up to the final drill. On the other hand if you slide the gas block on the barrel, mark the spots on the barrel through the gas blocks holes. Then take it over to a drill press and try to drill on the spots with the drill trying to walk around the round barrel and no clamping you will be real lucky to not have a canted gas block. When done this way, as previously mentioned, you end up with a clamped on gas block anyway so you can hide the bubba'ed dimples and have the ability to adjust the gas block to perfect alignment. There are widely varying degrees of talent and tools out there so be careful about encouraging everybody to "just do it yourself, it's easy."
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Posted: 3/2/2021 11:44:19 AM EDT
[#29]
With no access to a dimple jig, the edge of a file will work in creating a groove or flat spot for the set screw to contact. And just what does this accomplish? All a dimple is good for is reducing the likelyhood that a gas block will rotate if impacted, as well as an aid to aligning the GB (provided the dimple is in the proper position). A dimple will not make set screws hold any tighter. A set screw such as that Tig pictured will make it's own mark and the likelyhood of a GB rotating with such is also minimized. Also, a set screw GB that is under a rail is not likely to be impacted and therefore not likely to rotate due to impact anyway. I have removed GB's that were installed without dimples, but rather with hardened point cutting set screws and they definitely left a "dimple" in the barrel, and weren't going anywhere. I file this under the same tab of importance as using a torque wrench on castle nuts, MEH |
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Posted: 3/2/2021 11:52:41 AM EDT
[#30]
Quote HistoryQuoted: And just what does this accomplish? All a dimple is good for is reducing the likelyhood that a gas block will rotate if impacted, as well as an aid to aligning the GB (provided the dimple is in the proper position). A dimple will not make set screws hold any tighter. A set screw such as that Tig pictured will make it's own mark and the likelyhood of a GB rotating with such is also minimized. Also, a set screw GB that is under a rail is not likely to be impacted and therefore not likely to rotate due to impact anyway. I have removed GB's that were installed without dimples, but rather with hardened point cutting set screws and they definitely left a "dimple" in the barrel, and weren't going anywhere. I file this under the same tab of importance as using a torque wrench on castle nuts, MEH Quote HistoryQuoted: With no access to a dimple jig, the edge of a file will work in creating a groove or flat spot for the set screw to contact. And just what does this accomplish? All a dimple is good for is reducing the likelyhood that a gas block will rotate if impacted, as well as an aid to aligning the GB (provided the dimple is in the proper position). A dimple will not make set screws hold any tighter. A set screw such as that Tig pictured will make it's own mark and the likelyhood of a GB rotating with such is also minimized. Also, a set screw GB that is under a rail is not likely to be impacted and therefore not likely to rotate due to impact anyway. I have removed GB's that were installed without dimples, but rather with hardened point cutting set screws and they definitely left a "dimple" in the barrel, and weren't going anywhere. I file this under the same tab of importance as using a torque wrench on castle nuts, MEH You covered one aspect of it. “All a dimple is good for is reducing the likelyhood that a gas block will rotate”. It has the potential to move along the length of the barrel aside from rotating. Heat, vibration, and a lot of air pressure all play a factor. For every action there is an equal and opposite reaction (Newtons 3rd Law). Given that a gas tube is properly connected, the gas block would move in the opposite direction of the BCG if not held in place. The margin for error is small. Remember the gas block need only misalign with the gas port for absolute failure of the entire system. In essence, these small components are the very heart and driving force behind the working design of the rifle. The fact that non of this is a new revelation and you likely already know all the above information, choosing to place little importance on it makes your opinion appear to be “MEH” at best. |
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Posted: 3/2/2021 2:32:58 PM EDT
[#31]
Quote HistoryQuoted: I can’t take anyone seriously who’s process of assembling a rifle is to see how little they can get away with or how many shortcuts can be taken. If you don’t understand how to do it yourself or don’t possess the tools, there is no shame in paying a professional to assemble your rifle or buying a factory built upper/lower. Who is more respectable? The novice who has identified his own lack of knowledge or the novice who thinks he has nothing left to learn? I think that the problem comes in where all of the described methods are "the only right way" for different professionals. I've never done anything aside from pinning FSBs. I know that it works. So, why would anyone conceive of dimpling their barrel and doing something that is less than the best? My guess is because there are other, perfectly acceptable ways of doing things right. It does no harm for people to talk about the pros and cons of these methods and what has or hasn't worked. It also serves to debunk the reasons some say you should or shouldn't follow a particular method. It seems that the very purpose of this forum is to help others figure these things out and be open minded enough to learn something along the way. |
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Posted: 3/2/2021 2:45:10 PM EDT
[#32]
Quote HistoryQuoted: I think that the problem comes in where all of the described methods are "the only right way" for different professionals. I've never done anything aside from pinning FSBs. I know that it works. So, why would anyone conceive of dimpling their barrel and doing something that is less than the best? My guess is because there are other, perfectly acceptable ways of doing things right. It does no harm for people to talk about the pros and cons of these methods and what has or hasn't worked. It also serves to debunk the reasons some say you should or shouldn't follow a particular method. It seems that the very purpose of this forum is to help others figure these things out and be open minded enough to learn something along the way. We don’t all get to be professionals, nor do I claim to be one. I only hope to learn from those that are. I start arguments here to hopefully learn something new or dispel obvious misconceptions. That’s why I don’t surf this forum for auto repair tips or medical advice. I’ll go seek that information where it is appropriate. This forum should be a place where good information on the subject matter is shared and bad information goes to die. I will agree that an open mind is vital to that process though. Open mindedness is never a replacement for fact or common sense however. |
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Posted: 3/2/2021 3:19:01 PM EDT
[#33]
It has the potential to move along the length of the barrel aside from rotating. Which will also be mitigated with a hardened point cutting set screw. |
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Posted: 3/2/2021 3:25:42 PM EDT
[#34]
Quote HistoryQuoted: I can’t take anyone seriously who’s process of assembling a rifle is to see how little they can get away with or how many shortcuts can be taken. If you don’t understand how to do it yourself or don’t possess the tools, there is no shame in paying a professional to assemble your rifle or buying a factory built upper/lower. Who is more respectable? The novice who has identified his own lack of knowledge or the novice who thinks he has nothing left to learn? If you don't push the novice into knowing better and to do it DIY, then what's the point of the "AR" ? To be honest, thus far all the suggestions seem valid, none are the best way. From a purely machinist viewpoint, I would use either set screw or clamp-on, I would then drill a hole perpendicular to bore axis that will accept a roll pin, hole drilled near edge of barrel so that ~50% of pin diameter was in the barrel. This affectively is like staking yet allows for ez removal if need be. If any screws came loose the pin would at least prevent block from moving off port alignment. That said, the knurled set screws with proper torque should suffice. Using Loctite may not be beneficial if high heat is anticipated. W/o a threadlocker I would still use a drop of water or rubbing alcohol in the hole of the GB, this effectively lubes the screw while being torqued to spec and then will eventually evaporate away. I mean if you really want a good locked-up set screw, use the basic iron/steel knurled set screw and then touch the threads with a bit of salty water before install, the iron-oxide that will form will lock-up the threads real good, and the oxide won't get destroyed until about 2800F when it melts. And then I wonder about 6061 aluminum screws, melting point near 1100F, but what if you cooled the screw in freezer before install, torqued it in, will it then get tighter as it expands more than the steel as the GB gets hotter? Hmmmmm. And last but not least, thread-lockers. Interesting that Loctite (Henkel) puts fastener diameter range spec onto their lockers. Blue-med is spec'd as 1/4"dia(min). Why is that? The GB set screw is smaller than 1/4", so why use Blue-med locker? I assume you can use it on smaller fastener, but you will not get the specified break-torque #'s they publish. Happy GB'ing it
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Posted: 3/2/2021 3:36:38 PM EDT
[#35]
Quote HistoryQuoted: My biggest problem with the dimple and set screw is the execution of the process. If dimpled in a Bridgeport mill with a clampable v-block and a precise method of finding bottom dead center of the barrel is performed the results are great. (Like it would be performed by a experienced gunsmith) You must also start with a center drill and progressively work up to the final drill. On the other hand if you slide the gas block on the barrel, mark the spots on the barrel through the gas blocks holes. Then take it over to a drill press and try to drill on the spots with the drill trying to walk around the round barrel and no clamping you will be real lucky to not have a canted gas block. When done this way, as previously mentioned, you end up with a clamped on gas block anyway so you can hide the bubba'ed dimples and have the ability to adjust the gas block to perfect alignment. There are widely varying degrees of talent and tools out there so be careful about encouraging everybody to "just do it yourself, it's easy." Skinning the cat comes many ways. Using a dimple jig should be bare minimum when dimpling. I perhaps do not even agree with the way most dimples are made, using a 5/32" drill bit. To me that's way too big for the intended purpose. A 1/16" 90deg drill that makes a crater 1-2 32nd deep is plenty when using a properly pointed set screw (90deg sounds good). But hey, it's just a crude pea shooter AR-[add your fav cal here]. |
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Posted: 3/2/2021 3:44:35 PM EDT
[#36]
Quote HistoryQuoted: In the time that it took to post this thread and read responses you could have dimpled your bbl. And 5x faster if it were a clamp-on. My only gripe about dimpling is, if you needed to change the GB to another set screw type, there's no guarantee that the existing dimple(s) is in the correct location for the new GB. The "should be" notion fails more often than we like it to. |
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Posted: 3/2/2021 4:14:11 PM EDT
[#37]
Quote HistoryQuoted: Skinning the cat comes many ways. Monty at Centurion Arms has method that I have interest in.....  Attached File |
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Posted: 3/2/2021 4:31:04 PM EDT
[#38]
Quote HistoryQuoted: If you don't push the novice into knowing better and to do it DIY, then what's the point of the "AR" ? To be honest, thus far all the suggestions seem valid, none are the best way. From a purely machinist viewpoint, I would use either set screw or clamp-on, I would then drill a hole perpendicular to bore axis that will accept a roll pin, hole drilled near edge of barrel so that ~50% of pin diameter was in the barrel. This affectively is like staking yet allows for ez removal if need be. If any screws came loose the pin would at least prevent block from moving off port alignment. That said, the knurled set screws with proper torque should suffice. Using Loctite may not be beneficial if high heat is anticipated. W/o a threadlocker I would still use a drop of water or rubbing alcohol in the hole of the GB, this effectively lubes the screw while being torqued to spec and then will eventually evaporate away. I mean if you really want a good locked-up set screw, use the basic iron/steel knurled set screw and then touch the threads with a bit of salty water before install, the iron-oxide that will form will lock-up the threads real good, and the oxide won't get destroyed until about 2800F when it melts. And then I wonder about 6061 aluminum screws, melting point near 1100F, but what if you cooled the screw in freezer before install, torqued it in, will it then get tighter as it expands more than the steel as the GB gets hotter? Hmmmmm. And last but not least, thread-lockers. Interesting that Loctite (Henkel) puts fastener diameter range spec onto their lockers. Blue-med is spec'd as 1/4"dia(min). Why is that? The GB set screw is smaller than 1/4", so why use Blue-med locker? I assume you can use it on smaller fastener, but you will not get the specified break-torque #'s they publish. Happy GB'ing it Quote HistoryQuoted: Quoted: I can’t take anyone seriously who’s process of assembling a rifle is to see how little they can get away with or how many shortcuts can be taken. If you don’t understand how to do it yourself or don’t possess the tools, there is no shame in paying a professional to assemble your rifle or buying a factory built upper/lower. Who is more respectable? The novice who has identified his own lack of knowledge or the novice who thinks he has nothing left to learn? If you don't push the novice into knowing better and to do it DIY, then what's the point of the "AR" ? To be honest, thus far all the suggestions seem valid, none are the best way. From a purely machinist viewpoint, I would use either set screw or clamp-on, I would then drill a hole perpendicular to bore axis that will accept a roll pin, hole drilled near edge of barrel so that ~50% of pin diameter was in the barrel. This affectively is like staking yet allows for ez removal if need be. If any screws came loose the pin would at least prevent block from moving off port alignment. That said, the knurled set screws with proper torque should suffice. Using Loctite may not be beneficial if high heat is anticipated. W/o a threadlocker I would still use a drop of water or rubbing alcohol in the hole of the GB, this effectively lubes the screw while being torqued to spec and then will eventually evaporate away. I mean if you really want a good locked-up set screw, use the basic iron/steel knurled set screw and then touch the threads with a bit of salty water before install, the iron-oxide that will form will lock-up the threads real good, and the oxide won't get destroyed until about 2800F when it melts. And then I wonder about 6061 aluminum screws, melting point near 1100F, but what if you cooled the screw in freezer before install, torqued it in, will it then get tighter as it expands more than the steel as the GB gets hotter? Hmmmmm. And last but not least, thread-lockers. Interesting that Loctite (Henkel) puts fastener diameter range spec onto their lockers. Blue-med is spec'd as 1/4"dia(min). Why is that? The GB set screw is smaller than 1/4", so why use Blue-med locker? I assume you can use it on smaller fastener, but you will not get the specified break-torque #'s they publish. Happy GB'ing it @CryptoKnight In your first paragraph you described what is commonly referred to as a pinned gas block. Thanks for validating what has already been suggested in this thread. That method is the industry standard for securing a gas block in the proper position. Some quality barrel manufacturers complete this task for the customer. Of the barrels I own, Ballistic Advantage, Daniel Defense, and Griffin Armament came with pre-drilled barrels/gas blocks & pin. There are others that do it as well. While slightly confused by your contradiction, your contribution is appreciated. |
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Posted: 3/2/2021 4:51:51 PM EDT
[#39]
Just pin it, a lot of barrel manufacturers now include pinned gas blocks with barrels.
Also on the whole loctite debate. My go to AR has a pinned gas block, but also has one set screw. I used blue loctite on this set screw and marked it. After 5k rounds and 2 carbine classes the set screw has not moved at all. |
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Posted: 3/2/2021 4:59:00 PM EDT
[#40]
Quote HistoryQuoted: Monty at Centurion Arms has method that I have interest in..... https://www.ar15.com/media/mediaFiles/416992/image1_jpeg_optimal_jpeg_jpg-1848454.JPG Is that keyed in place? THAT is interesting. Seriously. |
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Posted: 3/2/2021 5:01:46 PM EDT
[#41]
Quote HistoryQuoted: Is that keyed in place? THAT is interesting. Seriously. Quote HistoryQuoted: Quoted: Monty at Centurion Arms has method that I have interest in..... https://www.ar15.com/media/mediaFiles/416992/image1_jpeg_optimal_jpeg_jpg-1848454.JPG Is that keyed in place? THAT is interesting. Seriously. Tab on GB interfaces with way on barrel. Perfect alignment of GP and some anti rotation protection inherently. Solid idea. Eta LINK |
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Posted: 3/2/2021 5:09:59 PM EDT
[#42]
Quote HistoryQuoted: Just pin it, a lot of barrel manufacturers now include pinned gas blocks with barrels. Also on the whole loctite debate. My go to AR has a pinned gas block, but also has one set screw. I used blue loctite on this set screw and marked it. After 5k rounds and 2 carbine classes the set screw has not moved at all. Nearly the same here. MY LPGBs have 2 set screws/red Loctite, also pinned with roll pin. I've yet to see a screw back out yet. |
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Posted: 3/2/2021 5:42:58 PM EDT
[#43]
SPR Mk 12 clamp on PRI sight base.
Clamp on plenty solid 
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Posted: 3/2/2021 5:47:47 PM EDT
[#44]
Quote HistoryQuoted: And last but not least, thread-lockers. Interesting that Loctite (Henkel) puts fastener diameter range spec onto their lockers. Blue-med is spec'd as 1/4"dia(min). Why is that? The GB set screw is smaller than 1/4", so why use Blue-med locker? I assume you can use it on smaller fastener, but you will not get the specified break-torque #'s they publish. Because following their advice results in more bottles of their product on your shelf. Lather, Rinse, REPEAT... double the sales! |
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Posted: 3/2/2021 5:55:12 PM EDT
[#45]
Is your gas block a bayonet mount?
Yes- Pin it No- Dimple or clamp or pin |
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Posted: 3/2/2021 7:31:30 PM EDT
[#46]
Quote HistoryQuoted: Ranked best to worst in my opinion 1: Pinned gas block 2: Dimpled barrel, staked screws 3: Dimpled barrel, rock-set screws 4: Dimpled barrel and tightened screws 5: No dimples, Screws only (Clamp on blocks vary in design and usage. I won’t speak on the durability of something I don’t own or use often) 1-2 are proven methods/safest 3 would suffice for duty use depending on conditions 4-5 is fine for plinking With no access to a dimple jig, the edge of a file will work in creating a groove or flat spot for the set screw to contact. Locktite is not really a reliable option when high levels of heat are involved. “Plinking” would probably be fine with red locktite Staked screws on gas block: https://www.ar15.com/media/mediaFiles/496867/53A3AE77-5BF3-41B9-A2EC-F714C42A5679_jpe-1847325.JPG ***Not my picture. I prefer to do mine from the side similar to a gas key*** Yea, I stake mine too after having one come loose in a class. Knurled cup screws, dimple, loctite...still came loose.  |
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Posted: 3/2/2021 8:55:23 PM EDT
[#47]
Quote HistoryQuoted: Monty at Centurion Arms has method that I have interest in..... https://www.ar15.com/media/mediaFiles/416992/image1_jpeg_optimal_jpeg_jpg-1848454.JPG Quote HistoryQuoted: Quoted: Skinning the cat comes many ways. Monty at Centurion Arms has method that I have interest in..... https://www.ar15.com/media/mediaFiles/416992/image1_jpeg_optimal_jpeg_jpg-1848454.JPG Would have though the gb issue would be more launching forward than rotating. Never seen either personally though, so what do I know. |
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Posted: 3/2/2021 8:58:54 PM EDT
[#48]
How many here have ever had a gas block of any kind fail in any way under any kind of use?
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Posted: 3/2/2021 9:03:19 PM EDT
[#49]
GOOD gas block screws will bite into the steel and raise a portion where they can't move if secured properly. Use new screws when you remove/reinstall.
A dimple under the gas port helps locate the one screw. GOOD clamp on blocks will hold if properly installed, you'll twist the barrel in the upper before it lets go. Use cheap parts and results may vary. Fail to install them properly and all bets are off. ETA: I've had two fail. One was a factory upper that wasn't built properly and the other was a DPMS aluminum gas block with reused screws on a test build. |
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Posted: 3/2/2021 9:16:17 PM EDT
[#50]
Quote HistoryQuoted: Is that an anti-rotation tab? That's something I've never seen before. Would have though the gb issue would be more launching forward than rotating. Never seen either personally though, so what do I know. Quote HistoryQuoted: Quoted: Quoted: Skinning the cat comes many ways. Monty at Centurion Arms has method that I have interest in..... https://www.ar15.com/media/mediaFiles/416992/image1_jpeg_optimal_jpeg_jpg-1848454.JPG Would have though the gb issue would be more launching forward than rotating. Never seen either personally though, so what do I know. Design is for alignment purposes. Surely there is some anti rotation effect inherent to the design but how much I couldn't say. It could definitely be reworked to be a workable feature designed into the setup. Just found it interesting in design and it'd take all user error out of alignment. GB comes with a dimple (pilot) for pin , BTW. And IIRC, no provision for set screws. Another pic with the hole drilled for pin:  Attached File |
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