View Full Version : Anyone have a high round-count with a factory BCM set screw gas block?
One of the blocks installed by BCM, not one you did yourself. Curious how they hold up over time and a few thousand rounds.
Jwknutson17
07-02-17, 20:52
I have a few factory BCM 11.5 uppers in the 4-7k range. No issues. With the higher round count they become even harder to remove.
I have a few factory BCM 11.5 uppers in the 4-7k range. No issues. With the higher round count they become even harder to remove.
The carbon must cement them on there.
Good to know your experience. Thanks.
jcalvert86
07-02-17, 21:32
I've had two uppers with 2500-3k rounds on each, no issues.
Please tell me that this is some kind of cruel joke?
Please tell me that this is some kind of cruel joke?
Actually I believe you guys (Sionics) use a similar technique from a conversation I had a while back with one of your people. It is simply a question regarding long-term/higher round count outcomes on gas blocks not pinned but instead dimpled, with knurled screws, and red Loctite applied. I've seen it mentioned here (likely as a matter of personal preference) that one's "go-to" gun should have a gas block pinned. I figure if there are enough guns out there with beaucoup rounds downrange set up in the [properly] non-pinned fashion then pinning may not be a prerequisite for a serious duty weapon. BCM is the best large vendor example of this, although Sionics is also a good reference.
methical20
07-04-17, 08:15
SOPMOD II rifles (10.3" and 14.5") see a fair bit of abuse and have set screw gas blocks.
I've wondered the same thing. Both my go to carbine's uppers started as BCM's with standard FSB. I ground and contoured them and painted before putting on a 12" rail. I went this route because I knew they would stay in place and just didn't have enough experience with the others.
Defaultmp3
07-04-17, 15:08
FWIW, from a conversation from Dave over at Defensive Creations:
If you don’t mind me asking, why are you pinning gas blocks? I know it seems to have become the norm but unless the weapon is going to be seeing seriously hard use (Full Auto) I personally think it is a bit overkill.
As long as a gas block is properly installed and the gun is maintained from time to time I personally have never seen one come loose. I have even gone as far as experimenting with aluminum gas blocks to shave a few onces of weight and never had one come loose.
I have been averaging between 8-12k a year in training and my rifles just run a double set screw gas block. Just an fyi.
Was the filthy 14 not set screw?
I think filthy 14 was an EAG upper with a fsb.
BrigandTwoFour
07-04-17, 16:01
Please tell me that this is some kind of cruel joke?
I'm honestly curious as well. It was common advice around here for a long time that a pinned gas block was the only way to go if you were going stake your life on a weapon. I figured things must have changed a bIt for low profile gas blocks covered by a rail given the prevalence of non-pinned gas blocks from BCM and others. But still, the gospel of pinned gas blocks is rampant.
justin_247
07-04-17, 16:01
I questioned set screw gas blocks, too, but I changed my mind after I saw this video from Mrgunsngear. He had a really hard time trying to remove the BCM gas block.
https://www.youtube.com/watch?v=IQ_0h_V9R9E
BrigandTwoFour
07-04-17, 16:03
I questioned set screw gas blocks, too, but I changed my mind after I saw this video from Mrgunsngear. He had a really hard time trying to remove the BCM gas block.
https://www.youtube.com/watch?v=IQ_0h_V9R9E
I suppose, as with most things, it really depends on the method used. I've seen several training AARs lately from people who had their set acrew gas blocks loosen up on them during class, turned my their guns into bolt actions. I don't know who did the install, though.
nightchief
07-04-17, 16:31
I have a BCM factory built 11.5" ELW upper with over 3K on it. It has run so far w/o fail in temps from 25 degrees to 105 degrees. Run both suppressed and unsuppressed. Gas block is tight. No "hard use" though (i.e. combat conditions). I'll can report back at the end of the year, as it should be approaching 5K by then.
NC
I suppose, as with most things, it really depends on the method used. I've seen several training AARs lately from people who had their set acrew gas blocks loosen up on them during class, turned my their guns into bolt actions. I don't know who did the install, though.
That would answer a lot of questions.
I think filthy 14 was an EAG upper with a fsb.
Oh yeah I think you're right.
OP - I've got two BCM uppers, both with 2.5-3k rounds which isn't a lot but I really think if there were issues, we'd have heard by now. BCM uppers are so prevalent that I have a hard time believing that their method doesn't work.
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Mrgunsngear
07-04-17, 18:00
I questioned set screw gas blocks, too, but I changed my mind after I saw this video from Mrgunsngear. He had a really hard time trying to remove the BCM gas block.
https://www.youtube.com/watch?v=IQ_0h_V9R9E
All set screw gas blocks are not created equal. Material, thread locker, depth of dimple, and fit of the gas block are all important in the security of it. Sionics and BCM have consistently the deepest dimples I've seen and I've removed 2x BCM gas blocks at this point in my life (never the Sionics) and it takes serious work to get them off. I've heard of people having to cut them off or send them to ADCO to get them removed...
http://www.youtube.com/watch?v=IQ_0h_V9R9E
So a properly installed, quality factory product (like BCM and Sionics that we know of), protected by a handguard/rail system, *should* be able to qualify as a weapon you could stake your life on?
My favorite AR has a 14.5" BCM ELW upper with 13" KMR (the original magnesium one), LMT Enhanced BCG, and Geissele SD-C trigger. It has the factory installed gas block under the KMR, so it's protected. Since it's my go-to (if you will) and it has other excellent enhancements I was just wondering about the utility of having it pinned. I don't have a FA lower so it's quite unlikely, even in a SHTF scenario, that I'd ever heat it up enough to undo the red Loctite. I've also just read about the depth of the dimples in Mrgunsandgear's post above. It sounds like just about any torque strong enough to twist it would also damage or ruin the gas block. To render the gun inoperable by means of the gas block moving, given that it is protected too, would likely deadline the weapon anyway.
I understand the above comments, my doubt was in my ability to do it right! I know I can use enough hammer for taper pins. I have mounted a few for friends and no complaints but all of mine are pinned. I'll try one for myself on my next build but ut will take a thousand rounds for me to feel as confident as I do with my pinned uppers.
I say this because there are several threads regarding the same question. There are a few companies that follow the dimple, Loctite, set screw method. I am unaware of any credible incidents of screws or blocks loosening. I have well over 30K rounds cumulative on several different uppers and they have had no issues.
We have several SIONICS demo uppers with thousands of rounds per upper on them and again no issues. I also feel confident in saying that BCM wouldn't do it, if Paul thought for a second it wasn't a secure means of doing so.
Actually I believe you guys (Sionics) use a similar technique from a conversation I had a while back with one of your people. It is simply a question regarding long-term/higher round count outcomes on gas blocks not pinned but instead dimpled, with knurled screws, and red Loctite applied. I've seen it mentioned here (likely as a matter of personal preference) that one's "go-to" gun should have a gas block pinned. I figure if there are enough guns out there with beaucoup rounds downrange set up in the [properly] non-pinned fashion then pinning may not be a prerequisite for a serious duty weapon. BCM is the best large vendor example of this, although Sionics is also a good reference.
I don't know the context of that advice or who said it, but BCM has been doing this method for at least 6 years and they get hard use from LE and civilians.
We have been doing the dimple/Loctite/set screw method for several years, whether it be an LE or commercial gun and I am unaware of any issues at all.
I'm honestly curious as well. It was common advice around here for a long time that a pinned gas block was the only way to go if you were going stake your life on a weapon. I figured things must have changed a bIt for low profile gas blocks covered by a rail given the prevalence of non-pinned gas blocks from BCM and others. But still, the gospel of pinned gas blocks is rampant.
All set screw gas blocks are not created equal. Material, thread locker, depth of dimple, and fit of the gas block are all important in the security of it. Sionics and BCM have consistently the deepest dimples I've seen and I've removed 2x BCM gas blocks at this point in my life (never the Sionics) and it takes serious work to get them off. I've heard of people having to cut them off or send them to ADCO to get them removed...
http://www.youtube.com/watch?v=IQ_0h_V9R9E
I have been running BCM guns for the most part exclusively for the last several years and never had an issue. I have also removed ONE BCM gas block and don't feel like tackling that again. So, to answer the OP's question, BCM does it the right way and I don't think you will ever hear of an issue with one of their blocks coming loose.
SeriousStudent
07-05-17, 19:23
So a properly installed, quality factory product (like BCM and Sionics that we know of), protected by a handguard/rail system, *should* be able to qualify as a weapon you could stake your life on?
......
Yes. Suppressed Sionics reduced gas port 11.5" AR leaning against my desk as I type this. It has a dimpled, Loctite, and set screw gas block.
It runs like a raped ape.
dramabeats
07-05-17, 23:23
So a properly installed, quality factory product (like BCM and Sionics that we know of), protected by a handguard/rail system, *should* be able to qualify as a weapon you could stake your life on?
My favorite AR has a 14.5" BCM ELW upper with 13" KMR (the original magnesium one), LMT Enhanced BCG, and Geissele SD-C trigger. It has the factory installed gas block under the KMR, so it's protected. Since it's my go-to (if you will) and it has other excellent enhancements I was just wondering about the utility of having it pinned. I don't have a FA lower so it's quite unlikely, even in a SHTF scenario, that I'd ever heat it up enough to undo the red Loctite. I've also just read about the depth of the dimples in Mrgunsandgear's post above. It sounds like just about any torque strong enough to twist it would also damage or ruin the gas block. To render the gun inoperable by means of the gas block moving, given that it is protected too, would likely deadline the weapon anyway.
The MK12 Mod 1 has a exposed set screw gas block. Marcus Luttrell's fell of a mountain and the gun still worked according to him..
I have a BCM upper with a VTAC fore end. Round count is 4,000-ish. It’s not a tack driver but it’s been solid and reliable. No issues with the gas block.
Perhaps it is worth noting that BCM's has a pinned GB. Not that it's needed, but a nice touch nevertheless.
https://www.bravocompanyusa.com/BCM-SPR-Mk-12-Mod-Bravo-1R-KAC-RAS-p/bcm-urg-mk12-1%20ras.htm
The MK12 Mod 1 has a exposed set screw gas block. Marcus Luttrell's fell of a mountain and the gun still worked according to him..
One of the blocks installed by BCM, not one you did yourself. Curious how they hold up over time and a few thousand rounds.
Pat Rogers had tons of BCM AR's with thousands of rounds. They never came loose. We also have NEVER pinned a GB on any of our personal rifles and they have never come loose. You just have to know how to do it properly.
C4
Perhaps it is worth noting that BCM's has a pinned GB. Not that it's needed, but a nice touch nevertheless.
https://www.bravocompanyusa.com/BCM-SPR-Mk-12-Mod-Bravo-1R-KAC-RAS-p/bcm-urg-mk12-1%20ras.htm
I'll wager they pin that particular model only because it's exposed and not underneath a handguard/rail system.
As someone mentioned, that's an exposed gas block and not in anyway protected.
Perhaps it is worth noting that BCM's has a pinned GB. Not that it's needed, but a nice touch nevertheless.
https://www.bravocompanyusa.com/BCM-SPR-Mk-12-Mod-Bravo-1R-KAC-RAS-p/bcm-urg-mk12-1%20ras.htm
It's an ass ache to remove a BCM build gas block. There's no worries about them holding up.
I saw in the MrGnG video above that there was a dimple for each set screw. I just did a rail swap and found only the rear one was dimpled. Upper was straight from BCM on s-i-l's rifle. His was a .750 instead of the .625, not sure if that's why the difference or not.
FWIW, I used a heat gun to break loose the loc-tite. While I don't think it would have ever come loose on its own, it wasn't that difficult to remove. About 3k through this one, which ain't exactly high round count..............
I saw in the MrGnG video above that there was a dimple for each set screw. I just did a rail swap and found only the rear one was dimpled. Upper was straight from BCM on s-i-l's rifle. His was a .750 instead of the .625, not sure if that's why the difference or not.
FWIW, I used a heat gun to break loose the loc-tite. While I don't think it would have ever come loose on its own, it wasn't that difficult to remove. About 3k through this one, which ain't exactly high round count..............
I would guess that if someone wondered about both screws being dimpled (and without totally removing the gas block) you'd just have to look at them and one *should* sit out further than the other if only one was dimpled (?).
I would guess that if someone wondered about both screws being dimpled (and without totally removing the gas block) you'd just have to look at them and one *should* sit out further than the other if only one was dimpled (?).
Concur, IF both screws are the same length.............they were on this one.
Concur, IF both screws are the same length.............they were on this one.
So you could tell something was amiss just by looking at it right?
So you could tell something was amiss just by looking at it right?
Don't think it was amiss, but different, yes.
I've removed a few BCM gas blocks and 1) they are always a PITA and 2) I don't recall ever seeing a barrel with more than a single dimple.
I've removed a few BCM gas blocks and 1) they are always a PITA and 2) I don't recall ever seeing a barrel with more than a single dimple.
Interesting. Would seem to think that if you used two set screws that you'd dimple it twice!
Sorry if this comment is not related to BCM, but I've bought barrels that only had one dimple and I would make a second dimple. Not exactly sure why this is the case, but perhaps the dimple directly opposite of the GP is universal and the spacing to the second dimple is varied. For instance, I've seen some GB's that are .450" and I've seen some .400" (and maybe there are even more than that). But, at any rate, I would have thought the BCM product would have had two dimples.
Interesting. Would seem to think that if you used two set screws that you'd dimple it twice!
Sorry if this comment is not related to BCM, but I've bought barrels that only had one dimple and I would make a second dimple. Not exactly sure why this is the case, but perhaps the dimple directly opposite of the GP is universal and the spacing to the second dimple is varied. For instance, I've seen some GB's that are .450" and I've seen some .400" (and maybe there are even more than that). But, at any rate, I would have thought the BCM product would have had two dimples.
Good point. While BCM likely doesn't make the barrels themselves they do know the spacing for the gas block they'll be using, so why not dimple both (especially if the barrel is already chucked up to do the first one).
There are several different spacings for GB set screws, but I think the BCM spacing of .460 is most common. I bought one of these .460 jigs and did a barrel (Not BCM) myself. I did two dimples for a .625" diameter GB. There is a sleeve that fits inside the .750" GB to make it .625" (see page two). The kit is very good quality and not cheap, but the results were very good and it came with the drill. There is a PRO version too.
http://brdengineering.com/t/gas-block-dimple-jigs?page=1
If you are like me and like your GO-TO rifles to have a pinned GB they make a BCM gas block jig for pinning your BCM gas block. I always used to buy BCM barrels with the permanent front sight gas block, then I'd simply shave the sight part off and be left with a double pinned GB. NEXT TIME, I'll buy a jig and pin the GB as well. Apparently it can be done with a hand drill, but I'll use my drill press.
GB drilling jigs and supplies. -->http://brdengineering.com/t/gas-block-drilling-jigs
Dimpling is done in house. They most likely only do one, for the same reason others do. If you switch blocks, the 2nd hole may not line up depending on the type of block.
Good point. While BCM likely doesn't make the barrels themselves they do know the spacing for the gas block they'll be using, so why not dimple both (especially if the barrel is already chucked up to do the first one).
Dimpling is done in house. They most likely only do one, for the same reason others do. If you switch blocks, the 2nd hole may not line up depending on the type of block.
Okay, that makes sense. I guess from a physics point of view, the relatively short length of the BCM and other gas blocks from front to rear could make a single screw dimple viable.
There are several different spacings for GB set screws, but I think the BCM spacing of .460 is most common. I bought one of these .460 jigs and did a barrel (Not BCM) myself. I did two dimples for a .625" diameter GB. There is a sleeve that fits inside the .750" GB to make it .625" (see page two). The kit is very good quality and not cheap, but the results were very good and it came with the drill. There is a PRO version too.
http://brdengineering.com/t/gas-block-dimple-jigs?page=1
If you are like me and like your GO-TO rifles to have a pinned GB they make a BCM gas block jig for pinning your BCM gas block. I always used to buy BCM barrels with the permanent front sight gas block, then I'd simply shave the sight part off and be left with a double pinned GB. NEXT TIME, I'll buy a jig and pin the GB as well. Apparently it can be done with a hand drill, but I'll use my drill press.
GB drilling jigs and supplies. -->http://brdengineering.com/t/gas-block-drilling-jigs
Thanks for that link. My buddy has all the gunsmithing equipment like a lathe and milling machine but no jig for that particular purpose. Might have to break down and buy one. I'll make him a deal: I buy it and you can keep it in the shop but have to pin all my gas blocks!
Can it be used with the gas block set screws already in place or do they have to be removed to pin it?
If this has been discussed before, please point me to the thread, but has anyone done any testing on how well the set screw gas blocks hold up over multiple high round count shooting sessions? Such as 400-500 rounds per day over a period of three to five more days? I'm asking because I have a couple of BCMs with 3-5k round counts but I typically shoot less than two hundred rounds per session, and it could be weeks apart between trips to the range. So do shooting schedules play any role in the reliability of the set screw gas block?
And would there be any disadvantages to getting the gas blocks pinned? I'm considering having my BCMs pinned but only for peace of mind.
Thanks for that link. My buddy has all the gunsmithing equipment like a lathe and milling machine but no jig for that particular purpose. Might have to break down and buy one. I'll make him a deal: I buy it and you can keep it in the shop but have to pin all my gas blocks!
Can it be used with the gas block set screws already in place or do they have to be removed to pin it?
I've done dimples, but I haven't done a pinning yet. I cannot, off the top of my head, think of a reason that it cannot be done with the screws in place. Thinking logically, that would be the way to do it. It would ensure alignment of the pin. You might want to remove the barrel from the receiver to make it easier to work with.
I saw a guy do it (youtube video) with a hand drill. He drilled the pin hole and used the reamer to make it a taper fit. Personally, I would just use a straight pin like Noveske does since it is an insurance policy and not the primary attachment mechanism.
If this has been discussed before, please point me to the thread, but has anyone done any testing on how well the set screw gas blocks hold up over multiple high round count shooting sessions? Such as 400-500 rounds per day over a period of three to five more days? I'm asking because I have a couple of BCMs with 3-5k round counts but I typically shoot less than two hundred rounds per session, and it could be weeks apart between trips to the range. So do shooting schedules play any role in the reliability of the set screw gas block?
And would there be any disadvantages to getting the gas blocks pinned? I'm considering having my BCMs pinned but only for peace of mind.
I've never read or heard of anyone having a PROPERLY DIMPLED and set screwed gas block coming loose (BCM). There are the creative people who do their own thing and have problems. That said, I'm obsessive about these things. I just built my first rifle with an un-pinned gas block. I may come to totally trust the set screws. Many on this forum shoot WAYYYYYYYYY more than I do and trust the BCM gas blocks.
If you are worried about yours, just take the hand guard off and check to make sure everything is copasetic.
I would obsess more about your ammo and mags.
If this has been discussed before, please point me to the thread, but has anyone done any testing on how well the set screw gas blocks hold up over multiple high round count shooting sessions? Such as 400-500 rounds per day over a period of three to five more days? I'm asking because I have a couple of BCMs with 3-5k round counts but I typically shoot less than two hundred rounds per session, and it could be weeks apart between trips to the range. So do shooting schedules play any role in the reliability of the set screw gas block?
And would there be any disadvantages to getting the gas blocks pinned? I'm considering having my BCMs pinned but only for peace of mind.
Jwknutson17
07-09-17, 17:57
If this has been discussed before, please point me to the thread, but has anyone done any testing on how well the set screw gas blocks hold up over multiple high round count shooting sessions? Such as 400-500 rounds per day over a period of three to five more days? I'm asking because I have a couple of BCMs with 3-5k round counts but I typically shoot less than two hundred rounds per session, and it could be weeks apart between trips to the range. So do shooting schedules play any role in the reliability of the set screw gas block?
And would there be any disadvantages to getting the gas blocks pinned? I'm considering having my BCMs pinned but only for peace of mind.
I have had over a thousand per day for 2+ days in a row and nothing to report about. Still rock solid. Even the ones I have installed personally are just as tough to get off as the BCM's. Never an issue when they are installed properly as many have said. Knurled Cup Point Set Screw is what you want to use. That's what BCM uses (they sent me 50 of them a while back,) and they have those "teeth" on the end to prevent them from coming out. Add red locktite and its never going anywhere. I have SLR gas blocks and used BCM set screws, with thousands of rounds on those, on NON-dimpled barrels and they never move either. I wouldn't personally use a smooth end set screw though.
Jwknutson17
07-09-17, 17:58
I would obsess more about your ammo and mags.
I'll second what Gunz said.
To echo what everyone else said, I've had no issues. I've been running low-pro GB's since the 90's and, if properly installed, they are very solid. Heat can and will break down the Loctite, but it seems the expansion of the cured material really cements everything in place despite the heat. The last time I removed the GB on my SPR, I literally had to hammer the thing off the shoulder (after removing the set screws) because the Loctite wicked under the GB and created a gap-filling seal.
Additional cost would be the only disadvantage of having it pinned, and the pinning would be unique to that GB/barrel combo.
If this has been discussed before, please point me to the thread, but has anyone done any testing on how well the set screw gas blocks hold up over multiple high round count shooting sessions? Such as 400-500 rounds per day over a period of three to five more days? I'm asking because I have a couple of BCMs with 3-5k round counts but I typically shoot less than two hundred rounds per session, and it could be weeks apart between trips to the range. So do shooting schedules play any role in the reliability of the set screw gas block?
And would there be any disadvantages to getting the gas blocks pinned? I'm considering having my BCMs pinned but only for peace of mind.
If this has been discussed before, please point me to the thread, but has anyone done any testing on how well the set screw gas blocks hold up over multiple high round count shooting sessions? Such as 400-500 rounds per day over a period of three to five more days? I'm asking because I have a couple of BCMs with 3-5k round counts but I typically shoot less than two hundred rounds per session, and it could be weeks apart between trips to the range. So do shooting schedules play any role in the reliability of the set screw gas block?
And would there be any disadvantages to getting the gas blocks pinned? I'm considering having my BCMs pinned but only for peace of mind.
S-i-l ran his aforementioned BCM at a class one weekend, about 950 rounds in 2 days, one of which was pushing 100°. Screws still as tight as Dick's hatband............as far as pinning, I think you're looking for an answer to an issue that doesn't exist.
if properly installed, they are very solid.
Several people in this thread have mention 'IF done properly'.
What exactly is the complete proper method. I can't see anything beyond this...
Dimple barrel
Place gas block
Apply 271 to threads
Insert and tighten screws
Let sit for 24 hours
What are the additional 'proper' nuances of this procedure?
I know there are some other numbers of Loctite made for sleeves and bearings and when you mention your block had to be hammered off. Perhaps a bearing locker was applied as well?
I'm just curious because often you see answers like... red Loctite and tighten the screws and you are good to go. But this one is... IF you do it properly, it works. So I'm just wondering what exactly is considered the best proper method, because I can't figure how you do it improperly if you did the few simple steps I mentioned above.
Jwknutson17
07-10-17, 10:27
Several people in this thread have mention 'IF done properly'.
What exactly is the complete proper method. I can't see anything beyond this...
Dimple barrel
Place gas block
Apply 271 to threads
Insert and tighten screws
Let sit for 24 hours
What are the additional 'proper' nuances of this procedure?
I know there are some other numbers of Loctite made for sleeves and bearings and when you mention your block had to be hammered off. Perhaps a bearing locker was applied as well?
I'm just curious because often you see answers like... red Loctite and tighten the screws and you are good to go. But this one is... IF you do it properly, it works. So I'm just wondering what exactly is considered the best proper method, because I can't figure how you do it improperly if you did the few simple steps I mentioned above.
I think properly in my book, when installing screws, is to a torque value, or making sure they are tight enough. Also, applying locktie "properly" to me is covering all the threads. Dimpling the barrel "properly" to me is using some sort of jig. I've seen some awkward wide dimples that the set screw could float around in. And some the exact size of the set screw so it falls directly into place with no chance of moving. I prefer to use the Knurled Cup Point Set Screw as I stated above, like what BCM uses, in any and all set screw gas blocks. These are my ideas of properly when talking about your list above. To me, its hard to mess it up, but I'm sure some folks can screw up the easiest of tasks.
This whole thing is a moot point, at least as far as BCM is concerned. They've been using dimpled barrels along with set screw gas blocks for quite a while now. It there was a problem, we would know.
No, I think you've got it down. I use 272 and it works great (higher temp rating), but 271 should be fine. I also torque my screws, but I don't want my number to be scrutinized as THE number, because it isn't. Depth of the dimple is important because you want full thread engagement on the block.
Several people in this thread have mention 'IF done properly'.
What exactly is the complete proper method. I can't see anything beyond this...
Dimple barrel
Place gas block
Apply 271 to threads
Insert and tighten screws
Let sit for 24 hours
What are the additional 'proper' nuances of this procedure?
I know there are some other numbers of Loctite made for sleeves and bearings and when you mention your block had to be hammered off. Perhaps a bearing locker was applied as well?
I'm just curious because often you see answers like... red Loctite and tighten the screws and you are good to go. But this one is... IF you do it properly, it works. So I'm just wondering what exactly is considered the best proper method, because I can't figure how you do it improperly if you did the few simple steps I mentioned above.
Its not that complicated, but sometimes numb nuts get it wrong. To me "properly" includes the materials that come with the GB too, that gas block material and set screws should be properly hardened and machined.
I don't know if the following would be considered "properly" installed, but this is how I have done it and feel comfortable with it.
1. Dimple the barrel so the barrel gas port lines up with the gas block port when the screws are tightened. I use a jig for the alignment/drilling process and believe that is the "proper" way to achieve alignment. Ensure the dimple(s) are the width of the screw. They do not have to be deep, they just need to allow the entire set screw face to engage the dimple.
2. Do a dry install to season the threads, set screw faces, and barrel dimple. Check for alignment with dimple(s). Remove the screws and GB.
3. Clean the set screw holes with acetone or brake cleaner. Something that won't leave any residue. Let dry.
4. Install the GB, cover the set screws with a semi-permanent thread locker like Red Loctite.
5. Install the screws, ensuring that they seat well into the dimple(s). I don't know what the torque should be, but I crank them down with a T handle. Not too tight as to strip the threads.
6. Let Loctite dry for a minimum of 24 hours. I usually end up letting them sit for several days.
7. Take out and shoot. If you don't have the ports aligned the GB will be crooked and the gas might be inadequate to cycle the rifle.
Pretty dang simple if you use care and the right tools. If I've got this wrong or someone can supply torque numbers, please speak up.
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