View Full Version : Non-Dimpled Barrel Gas Block Installation 2019
I am always amazed in 2019 that people still do not know about dimpling barrels for gas block installation or people who constantly say "it's not necessary". This upper was recently sent to me after the owner noticed it was no longer working. It was home assembled and he had no idea that the barrel should be dimpled. The set screws had also not been Loctited, although both screws were tight when I removed them. One can clearly see how far the gas block shifted. According to the owner it had several hundreds of rounds through it until this happened.
I can say with almost 99% certainty, that a properly dimpled barrel, with correct set screws and Loctite will not come loose. I have tens of thousands of cumulative rounds through multiple uppers, and that doesn't include the multiple weapons that we have at SIONICS that are used in demos with tens of thousands of rounds through them.
Sadly there are manufacturer's doing this as well as using aluminum gas blocks on their uppers.
https://i.imgur.com/Lw13GkM.jpg
https://i.imgur.com/96ALyKf.jpg
https://i.imgur.com/4RyyHqB.jpg
Looks like once it loosened and came out of alignment, the gas key drove it forward. Yeah, do it right the first time.
Hearsay I tell ya, hearsay!
Seriously, thanks for sharing. A good reminder what to look for and of course, buy good stuff from the get go to avoid issues like this.
I can say with almost 99% certainty, that a properly dimpled barrel, with correct set screws and Loctite will not come loose
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Looks like once it loosened and came out of alignment, the gas key drove it forward. Yeah, do it right the first time.
I agree...rather than paying to have the barrel dimpled, pay to have the gas block pinned.
I agree...rather than paying to have the barrel dimpled, pay to have the gas block pinned.
I believe the point IG was making was in reference to home builders. Far easier to dimple the barrel than to pin the gas block for most guys. But I agree, if paying to have your upper assembled, pinning is preferable.
IG is there any particular jig for dimpling the barrel that you prefer over others?
Or buy barrels from manufacturers that dimple their barrels from the start.
I agree...rather than paying to have the barrel dimpled, pay to have the gas block pinned.
Some manufacturers are actually using aluminum gas blocks? Don't they sooner rather later erode to the point of non-functionality?
titsonritz
05-11-19, 20:40
IG is there any particular jig for dimpling the barrel that you prefer over others?
I'd be interested in your recommendation as well.
Or buy barrels from manufacturers that dimple their barrels from the start.
Yea but it’s not hard to dimple a barrel.
The SLR kits work well and are like 30 bucks
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I second the SLR, simple and cheap.
everready73
05-12-19, 08:23
Some manufacturers are actually using aluminum gas blocks? Don't they sooner rather later erode to the point of non-functionality?
I know the dpms Oracle has one. I am sure some other low tier brands are using them
Yea but it’s not hard to dimple a barrel.
The SLR kits work well and are like 30 bucks
I can get two barrels dimpled for that. Or, I can have my gas block pinned for less than $30. I’d prefer to go that route.
I can get two barrels dimpled for that. Or, I can have my gas block pinned for less than $30. I’d prefer to go that route.
Ok and?
But just think. I’ve self sufficiency ruled the day we wouldn’t have threads like this.
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Ok and?
But just think. I’ve self sufficiency ruled the day we wouldn’t have threads like this.
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Does it count as self-sufficiency if you pin your own?
Does it count as self-sufficiency if you pin your own?
Only if you don’t post about it online. There’s always a catch I’m afraid.
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Sparky5019
05-12-19, 14:04
Home shop or not. There’s no substitute for doing a job properly. A little learning can be a dangerous thing. ��
Only if you don’t post about it online. There’s always a catch I’m afraid.
Then I'm good to go, I asked a question, made no statement. :)
I will tell you that my wife questioned the drill press, as a result I do everything from punching holes in donuts to pinning unnamed objects onto other unnamed objects on the drill press. I also trim my nails on the table saw to justify that expense.
Signed,
Stubby
I have the original BRDE jig as well as their new multi-jig. Both have proven to be fully functional.
IG is there any particular jig for dimpling the barrel that you prefer over others?
I have the original BRDE jig as well as their new multi-jig. Both have proven to be fully functional.
This one? https://brdengineering.com/products/2-universal
I also have one of BRD's 1A jigs, and it still does the job.
Their 1A-HT jig appears quite flexible.
Craftsman62
05-13-19, 14:14
IG is there any particular jig for dimpling the barrel that you prefer over others?
SLR Rifleworks is the one that I use...
https://slrrifleworks.com/index.php?route=product/product&product_id=579
I’m not trying to be a smart-ass, but in 2019 why aren’t most companies pinning?
I understand that most home builders would rather dimple for ease of use. If I build, I send the barrel off to get pinned, and I avoid products where a compay doesn’t pin the gasblock. This website used to argue straight vs tapered. Am I missing something? Is there a benefit to a set screw/dimpled over pinning?
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Properly installed, set screw installations are very reliable.
Gas blocks rarely wear out, but if for some reason the gas block does need to be replaced, such as installing an adjustable gas block to control gas when a suppressor is installed, the new gas block will align with the dimple driectly below the gas port. It's much harder to get a new gas block to align with the old cross pin hole.
Sparky5019
05-13-19, 15:45
I’ve got BRDE jigs but the SLR ones are excellent as well.
Again, with good tools like these that align at least the 1st dimple directly opposite the gas port, I don’t get why people don’t use them. In a pinch, with no access to my mill, I’ve used a damn hand drill with perfect results.
[emoji2361][emoji2361][emoji2361] lol.
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I’m not trying to be a smart-ass, but in 2019 why aren’t most companies pinning?
I understand that most home builders would rather dimple for ease of use. If I build, I send the barrel off to get pinned, and I avoid products where a compay doesn’t pin the gasblock. This website used to argue straight vs tapered. Am I missing something? Is there a benefit to a set screw/dimpled over pinning?
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Because people tinker with their guns too much and set screws are usually removable with hand tools.
Because people tinker with their guns too much and set screws are usually removable with hand tools.
That’s what I thought. I don’t tinker. I want the gun done right, from the factory.
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Am I missing something? Is there a benefit to a set screw/dimpled over pinning?
I’ve heard a theory that pinning can harm a barrel’s accuracy. I don’t really put much stock in it because my most accurate AR is pinned. In any case pinning is the best option for almost everyone, and most of my rifles are pinned. The rifles do not limit my marksmanship.
It's much harder to get a new gas block to align with the old cross pin hole.
I’m having this problem currently with a DD barrel I snagged secondhand. I may just dimple it.
Because people tinker with their guns too much and set screws are usually removable with hand tools.
Out of a half dozen BCM set screw gas blocks I have removed, I've had to drill out the set screws every single time. No amount of good quality allen wrenches and heat (within reason) would get them out. I've had the exact same results with every set screw gas block I've installed myself. I'd just as soon remove a damn pinned FSB as trying to get properly done set screws out.
To be fair, that's probably because BCM (and you) essentially install them permanently (IMHO property). If I remove a GB I expect to replace it, it's not an area to be dicking around with.
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titsonritz
05-13-19, 22:25
Out of a half dozen BCM set screw gas blocks I have removed, I've had to drill out the set screws every single time. No amount of good quality allen wrenches and heat (within reason) would get them out. I've had the exact same results with every set screw gas block I've installed myself. I'd just as soon remove a damn pinned FSB as trying to get properly done set screws out.
This. Popped out a couple taper pins is WAY less hassle than removing properly installed set screws, not even close really. As mentioned, be sure you have replacement screws on hand, you are most likely going to need them, taper pin pop right back in.
Sparky5019
05-13-19, 22:32
Damn. I’m good with taper pins but shit! The problems Doug has had with BCM screws, I’ve had with BCM taper pins. I’ve got all the good tools and still have to cut the FSB off occasionally because they won’t move. Lol.
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That's to pin the gas block.
https://brdengineering.com/products/pro-gas-block-dimple-jig-0460-centers-vltorbcmrainier
https://brdengineering.com/products/hex-triple-gas-block-dimple-jig
This one? https://brdengineering.com/products/2-universal
5/16" Starrett punch and a 1" brass hammer makes pretty quick work of those given that the FSB is properly secured. The key is be sure the surface you are working on doesn't "give" and absorb precious energy. If this is the case, you could bang on it with a 4lb engineers hammer pretty much all damn day.
Damn. I’m good with taper pins but shit! The problems Doug has had with BCM screws, I’ve had with BCM taper pins. I’ve got all the good tools and still have to cut the FSB off occasionally because they won’t move. Lol.
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Sparky5019
05-14-19, 09:47
Dude. I know the tools and the techniques. Every BCM set of pins yet have laughed at them. I typically use a punch and a brass ball peen and they rarely every loosen. Orange taper pin block or vise makes no difference. Just my curse I guess.
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BCM's are indeed tight, but I've never had any issue that would require cutting. So please forgive me if I may have insulted your toolbox or technique. :agree:
Dude. I know the tools and the techniques. Every BCM set of pins yet have laughed at them. I typically use a punch and a brass ball peen and they rarely every loosen. Orange taper pin block or vise makes no difference. Just my curse I guess.
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Sparky5019
05-14-19, 10:01
Lol you didn’t. I had an old stout Starrett cup tip nail set that they destroyed so I’m left using inferior modern punches. That thing punched out many until the 1st couple BCMs. Lol.
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I've used those cup tip punches back in the 90's. They chip, slip, and don't seem to transfer the energy like a fat, flat punch. Never again!
Lol you didn’t. I had an old stout Starrett cup tip nail set that they destroyed so I’m left using inferior modern punches. That thing punched out many until the 1st couple BCMs. Lol.
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Sparky5019
05-14-19, 10:25
I hear ya. I’ve found they give a good start then the flat ones can drive them out. I’ve had flats slip off and mar things. The key is for the cup tip to be hard enough and not deform. A real challenge these days.
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When I was working at a shop that stocks BCM rifles and uppers I had to remove quite a few gas blocks/FSBs as people were always bringing them in to swap out handguards, etc. I never had drill any out though. With the low-pro gas block I would have to put the the tip of the flame from a propane torch directly on the head of the screw and hold it there until I could see the thread locker (presumably red Loctite) start to bubble out around the top edge. It would then screw right out. With that particular little torch it usually took at least 30-45 seconds. With the one I have at home it only takes around 15-20 seconds. With the pinned FSPs, the trick is to put it in an AR armorer block on a sturdy table and use a ball peen hammer that is at least 16 oz. along with a punch that is way larger (both longer and fatter) than you think you need. Hitting it one or two solid times with the big ball peen hammer and punch never failed to start the pin moving and then I could easily tap it the rest of the way out using a smaller punch.
Yes, the torch is your friend when it comes to removing loctited screws.
This is especially true when removing a muzzle device that somebody "secured" with red loctite.
Which loctite is recommended for GB set screws?
Which loctite is recommended for GB set screws?
I've always used red for gas block set screws. I don't think any other kind can withstand the heat.
I've always used red for gas block set screws. I don't think any other kind can withstand the heat.
Blue and Red general purposes have the same heat tolerance but different holding strengths. There are high temp and ultra high temp variants of both holding strengths. Unless you’re mag dumping, regular loctite (red) should be fine (360 F).
gunnerblue
05-18-19, 17:35
Which loctite is recommended for GB set screws?
Rocksett works as well. It’s designed to withstand high temps but is as hard to remove as red loctite
Loctite 272 (high temp red - up to 450F)
Which loctite is recommended for GB set screws?
That's not completely true. Rocksett has far less breakaway torque. The problem most people experience with either product is application amount and surface prep. However, the specs don't lie.
Rocksett works as well. It’s designed to withstand high temps but is as hard to remove as red loctite
gunnerblue
05-20-19, 12:03
Loctite 272 (high temp red - up to 450F)
That's not completely true. Rocksett has far less breakaway torque. The problem most people experience with either product is application amount and surface prep. However, the specs don't lie.
Thanks for the correction- I mistyped and meant to say that Rocksett is NOT very difficult to remove. Ive never had a muzzle device come loose when using it.
Do you guys use a torque screwdriver on the GB set screws or just an Allen wrench? If a torque screwdriver, what torque setting?
Others might, I do not use a torque screwdriver. I just clean/prep the threads on both the screws and GB, apply a TINY DOT of Rocksett (or Loctite) to the threads of the screws and snug down finger tight. I do let the wrench tail slightly bend a little but never to the point that it's going to snap, barber pole twist, or strip the head. Just "snug tight". That way it's not going to move under fire but I'll be able to remove them if I need to, and sometimes it is not an easy thing to do.
I'd like to hear what others do as this is just the way I do it.
Do you guys use a torque screwdriver on the GB set screws or just an Allen wrench? If a torque screwdriver, what torque setting?
Let me add that good GB screws have knurling on the tips which bite into the barrel. Together with the thread locker, it makes for a very secure combo. Good luck.
Others might, I do not use a torque screwdriver. I just clean/prep the threads on both the screws and GB, apply a TINY DOT of Rocksett (or Loctite) to the threads of the screws and snug down finger tight. I do let the wrench tail slightly bend a little but never to the point that it's going to snap, barber pole twist, or strip the head. Just "snug tight". That way it's not going to move under fire but I'll be able to remove them if I need to, and sometimes it is not an easy thing to do.
I'd like to hear what others do as this is just the way I do it.
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