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Posted: 1/14/2019 11:28:01 AM EDT
[#1]
I use blue and have no issues.
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Posted: 1/14/2019 11:38:37 AM EDT
[#2]
All my FSBs and gas blocks are pinned and I don’t worry about it. Ballistic advantage will supply and pin a gas block to a new barrel purchase for +$40.
If you go with red or rock set, change the grub screws out for hex-head screws or torx-head cap screws. Makes removal easier later. |
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Posted: 1/14/2019 12:43:53 PM EDT
[#3]
I changed out my PA10 Gas block for an SLR Adjustable. I used Red Loctite threadlocker. Days later, I removed the SLR gasblock with the use of a heat gun. I heated the gas block for a couple of minutes.
Slow & Steady pressure with a hex wrench, and it unscrewed without trouble. YMMV |
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Posted: 1/14/2019 1:05:05 PM EDT
[#4]
Strength formulation (color) is less important than the temperature rating. I use high heat blue for gas block set screws and high heat purple (low strength, small fastener) vibra-tite for every thing else. I’ve never had a fastener come loose...
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Posted: 1/14/2019 1:41:42 PM EDT
[#5]
Dimpling, torque, and standard blue. It's worked so far.
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Posted: 1/14/2019 2:03:34 PM EDT
[#6]
Loctite 246. High Temperature medium strength. Never had any issues.
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Posted: 1/14/2019 2:07:38 PM EDT
[#7]
Cross thread it and you will never have to worry about it backing out
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Posted: 1/14/2019 2:50:21 PM EDT
[#8]
I use rocksett or red loctite.
If it is a “combat” rifle then I will use red once I know everything is set up properly. All others get rocksett because every once in a while I tear them down or change parts. Using a little rocksett on the gas block screws allows me to break the bond with tools but without the need for a blowtorch or anything too extreme. I tried blue locker but it just got all gummy and required almost no force to unscrew-as if there was no threadlocker at all. My understanding is that blue is not formulated to handle the heat. Rocksett works well that it is not impossible to undo with tools and it can handle the heat, |
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Posted: 1/14/2019 4:32:23 PM EDT
[#9]
I use red loctite. But I have an oxy/acetylene rig, so removal is quick and easy.
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Posted: 1/14/2019 4:54:55 PM EDT
[#10]
Quote HistoryQuoted:
I use rocksett or red loctite. If it is a “combat” rifle then I will use red once I know everything is set up properly. All others get rocksett because every once in a while I tear them down or change parts. Using a little rocksett on the gas block screws allows me to break the bond with tools but without the need for a blowtorch or anything too extreme. I tried blue locker but it just got all gummy and required almost no force to unscrew-as if there was no threadlocker at all. My understanding is that blue is not formulated to handle the heat. Rocksett works well that it is not impossible to undo with tools and it can handle the heat, It has the highest temperature rating. IMO if we are saying that the muzzle device needs this type of thread locker then why not use it on other parts that may get pretty hot. If I want to take the gas block/muzzle device off I just put the entire barrel assembly in a pot of boiling water for an hour or more if needed and then wrench them off. I've never had a gas block set screw come loose using this method. However, whenever I build a rifle I always use SLR gas blocks. I drill a #31 hole and pin them as well as set screw them. |
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Posted: 1/14/2019 8:41:18 PM EDT
[#11]
The vast majority of my GBs with set screws are neither on dimpled barrels or with thread locker. They've held up fine. If you choose to dimple you might get a little better bite using screws with a knurled cup point.
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Posted: 1/14/2019 8:46:30 PM EDT
[#12]
Red Loctite will melt in <10-sec with a propane torch. Oxy/Acetylene?? Dayum!!
 
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Posted: 1/14/2019 8:50:28 PM EDT
[#13]
I've used red in the past but I am going to use Loctite 2422 high heat blue thread locker on the next gas block I install.
The Blue 2422 is high heat resistant, up to 650 degrees, but medium strength so the screws remove as easily as medium strength blue. |
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Posted: 1/14/2019 11:12:25 PM EDT
[#14]
Permatex Blue is all I've used, nothing's shifted or backed out. Henderson Defense said in their high round count thread that torque alone has held them on, and carbon fouling essentially glues everything in place.
Another thing I've read is that the military doesn't pin, dimple, or use sealant on the Mk12 gas block, but they do stake the screws. |
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Posted: 1/14/2019 11:39:27 PM EDT
[#15]
Quote HistoryQuoted:
Red Loctite will melt in <10-sec with a propane torch. Oxy/Acetylene?? Dayum!! |
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Posted: 1/15/2019 5:11:21 AM EDT
[#16]
Quote HistoryQuoted:
Another thing I've read is that the military doesn't pin, dimple, or use sealant on the Mk12 gas block, but they do stake the screws. Use one drop Loctite 242 per set screw and torque set screw to 25 in lb. Barrels were being dimpled by Crane before send me replacements. New FN 10.3" and 14.5" are dimpled by the factory before sending to me to install. I install by the TRS/TM standards. Staking of set screws is not in there. ETA Appendix H was written by Crane. CD |
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Posted: 1/15/2019 12:22:21 PM EDT
[#17]
Quote HistoryQuoted:
I've used red in the past but I am going to use Loctite 2422 high heat blue thread locker on the next gas block I install. The Blue 2422 is high heat resistant, up to 650 degrees, but medium strength so the screws remove as easily as medium strength blue. Switched to 2422 the past couple uppers I've assembled. One dimple, loctite 2422, and 25 in/lbs on the knurled screws. |
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Posted: 1/15/2019 12:28:06 PM EDT
[#18]
I use 242, turn the hex key into a candy cane, and remove with a propane torch.
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Posted: 1/15/2019 6:59:12 PM EDT
[#19]
Quote HistoryQuoted:
I use 242, turn the hex key into a candy cane, and remove with a propane torch. |
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Posted: 1/16/2019 9:15:18 AM EDT
[#20]
Quote HistoryQuoted: Says who as they are wrong? The Mk12 TRS states if gas block maintenance is needed return to Crane. The M4A1 URG TRS where installation of the Mk12 gas block is shown in Appendix H. Use one drop Loctite 242 per set screw and torque set screw to 25 in lb. Barrels were being dimpled by Crane before send me replacements. New FN 10.3" and 14.5" are dimpled by the factory before sending to me to install. I install by the TRS/TM standards. Staking of set screws is not in there. ETA Appendix H was written by Crane. CD |
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Posted: 1/16/2019 11:40:04 AM EDT
[#21]
Quote HistoryQuoted: Says who as they are wrong? The Mk12 TRS states if gas block maintenance is needed return to Crane. The M4A1 URG TRS where installation of the Mk12 gas block is shown in Appendix H. Use one drop Loctite 242 per set screw and torque set screw to 25 in lb. Barrels were being dimpled by Crane before send me replacements. New FN 10.3" and 14.5" are dimpled by the factory before sending to me to install. I install by the TRS/TM standards. Staking of set screws is not in there. ETA Appendix H was written by Crane. CD |
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Posted: 1/16/2019 11:51:33 AM EDT
[#22]
I use Loctite Blue 248 in stick/paste form.
Absolute hands down best way to apply. Put fastener on allen key, touch against paste and spin. Perfect application every time. I use it at work everyday as well. I also change out ALL of the set screws on my gas blocks to these from McMaster Carr. Alloy Steel Knurl-Grip Cup-Point Set Screw Black Oxide, 10-32 Thread, 3/16" Long I've never had one even think about coming loose. To remove, I use a small pencil torch to warm the loctite. Then use the appropriate bit in a bit driver to remove. While you're at McMaster ordering your new screws, do yourself a favor and buy some keys and bits in bulk. They are super good quality and cheap as shit. I think I ordered 10 of each and have yet to need to change one due to wear. 6" key 3" key 3/32 bits |
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Posted: 1/16/2019 8:51:18 PM EDT
[#23]
I contacted Faxon about their recommended method and they told me to use red loctite. Haven't had any issues with it
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Posted: 1/16/2019 10:04:47 PM EDT
[#24]
Quote HistoryQuoted:
I use Loctite Blue 248 in stick/paste form. Absolute hands down best way to apply. Put fastener on allen key, touch against paste and spin. Perfect application every time. I use it at work everyday as well. I also change out ALL of the set screws on my gas blocks to these from McMaster Carr. Alloy Steel Knurl-Grip Cup-Point Set Screw Black Oxide, 10-32 Thread, 3/16" Long I've never had one even think about coming loose. To remove, I use a small pencil torch to warm the loctite. Then use the appropriate bit in a bit driver to remove. While you're at McMaster ordering your new screws, do yourself a favor and buy some keys and bits in bulk. They are super good quality and cheap as shit. I think I ordered 10 of each and have yet to need to change one due to wear. 6" key 3" key 3/32 bits Unrelated to gas block set screws but I also have been using coiled roll pins on all the roll pins in the gun. Easier to install and higher breaking strength. |
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Posted: 1/16/2019 10:48:17 PM EDT
[#25]
Quote HistoryQuoted: From your experience has this been a pretty rock solid mounting technique in comparison to pinned? I only ask because all of my 556 rifles have a pinned mk12 gas block while my new 300BO build (using an 8.2 Rosco Bloodline barrel) is only dimpled. I was disassembling an upper with a pinned/set screwed mk12 gas block. I knocked out the pin, but forgot to take out the set screws underneath.
Barrel was set in a vice and I was whacking the gb with a 6in. stretch of 2x4 and a 5lb hammer. I was hitting this thing so hard the wood compacted inside of the hole where the gas tube goes and it split the 2x4 in half. Realizing my mistake, I took the set screws out and the gb popped right off. I expected the set screws to mar the dimple spots, but nothing. Not a single mark lol. As long as the set screws are properly torqued with a drop of loctite, that thing isn't going anywhere. |
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Posted: 1/17/2019 12:18:51 AM EDT
[#26]
Red Loctite.
I used to use Rocksett and stopped after stripping out too many set screws. You will get a gas block into the temp range where you will weaken it, but it still needs to get broken free if you want the fastener to come out - and a proper set screw with a serrated cup head isn't going to want to go anywhere anyways. If you think you're going to get a barrel hot enough to actually burn the red Loctite out, or you're expecting the sorts of vibration you get on something select-fire, then you should really be pinning the gas block. Clamp gas block get Rocksett, though, the screws are less of an issue if they get stuck. |
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Posted: 1/17/2019 12:26:38 AM EDT
[#27]
I used to use Rocksett but that shit is such a bitch to remove. I've twisted a couple allen wrenches and the set screws will not budge! Like others have said, you'll need to torch them if you want them to move. I'm sticking with blue loctite.
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Posted: 1/17/2019 11:45:50 AM EDT
[#28]
Quote HistoryQuoted:
I use blue and have no issues. |
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Posted: 1/18/2019 10:31:33 AM EDT
[#29]
Voted for blue/242, that's what I use.
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Posted: 1/18/2019 12:16:51 PM EDT
[#30]
torque/dimple
no need for locktite |
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Posted: 1/18/2019 12:23:29 PM EDT
[#31]
Quote HistoryQuoted: From your experience has this been a pretty rock solid mounting technique in comparison to pinned? I only ask because all of my 556 rifles have a pinned mk12 gas block while my new 300BO build (using an 8.2 Rosco Bloodline barrel) is only dimpled.  Attached FileCD |
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Posted: 1/18/2019 9:19:05 PM EDT
[#32]
Quote HistoryQuoted: Never seen a pinned Mk12 gas block in the field. Since 14' I have never seen or had a Mk12 gas block come undone. After the barrel is shoot out lately however, its quicker and easier to cut the barrel in half to remove the DD barrel nut than trying to get a stuck gas block off. Broke my MagPull BEV block as I was trying to remove a stuck gas block (yes, set screws removed). https://www.AR15.Com/media/mediaFiles/32677/IMG_5956_jpg-812090.JPG CD |
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Posted: 1/18/2019 10:09:02 PM EDT
[#33]
Quote HistoryQuoted:
The vast majority of my GBs with set screws are neither on dimpled barrels or with thread locker. They've held up fine. If you choose to dimple you might get a little better bite using screws with a knurled cup point. There is no advantage to using dimpling beyond creating an index point to align the hole in the block with the gas port. Some barrels, Lilja for instance, have a machined flat exactly 180 degrees from the port. If present, it helps align the block and gives the set screws something flat to dig into. The poll should include a "just properly torque that set screws, they will hold" option. |
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Posted: 1/18/2019 11:33:31 PM EDT
[#34]
Quote HistoryQuoted:
I use 242, turn the hex key into a candy cane, and remove with a propane torch.  Attached File |
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Posted: 1/19/2019 1:04:59 AM EDT
[#35]
Quote HistoryQuoted: Never seen a pinned Mk12 gas block in the field. Since 14' I have never seen or had a Mk12 gas block come undone. After the barrel is shoot out lately however, its quicker and easier to cut the barrel in half to remove the DD barrel nut than trying to get a stuck gas block off. Broke my MagPull BEV block as I was trying to remove a stuck gas block (yes, set screws removed). https://www.AR15.Com/media/mediaFiles/32677/IMG_5956_jpg-812090.JPG CD |
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Posted: 1/19/2019 1:23:27 AM EDT
[#36]
Quote HistoryQuoted: Those look like converted M4 barrels. Are they being replaced with the SOCOM profile barrels as they wear out? CD |
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Posted: 1/19/2019 12:55:21 PM EDT
[#37]
Quote HistoryQuoted:
torque/dimple no need for locktite |
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Posted: 1/19/2019 12:57:57 PM EDT
[#38]
Quote HistoryQuoted: Agree. If the gas block has true concave cup tipped set screws, they flatten out and dig into the barrel, cutting a round ring in the mrtal that you can see if later removed. They don't move unless you want them to. No need to use thread locker or Rocksett. There is no advantage to using dimpling beyond creating an index point to align the hole in the block with the gas port. Some barrels, Lilja for instance, have a machined flat exactly 180 degrees from the port. If present, it helps align the block and gives the set screws something flat to dig into. The poll should include a "just properly torque that set screws, they will hold" option. Anyways, here is the one I just did yesterday. It is an SLR Non-adjustable with two dimples on the barrel, rocksett, and a coil pin. I like redundancy. I've personally never had a problem with Rocksett. If it doesn't want to budge I just put it in a pot of boiling water for an hour. The screws/muzzle device turn with ease after that. 
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Posted: 1/19/2019 1:10:37 PM EDT
[#39]
Here is the blaster that got the above treatment.
Just waiting on the Q Cherry Bomb to come into stock at RSR or Lipseys and then toss the optic on with the Geissele 1.93" T2 Mount. Q Trash Panda is also out of stock. Then maybe a M300. 
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Posted: 1/19/2019 3:39:23 PM EDT
[#40]
Yeah... That aint moving. Nice!
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Posted: 1/19/2019 4:07:26 PM EDT
[#41]
Quote HistoryQuoted:
Dimpling, torque, and standard blue. It's worked so far. |
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Posted: 1/19/2019 7:56:39 PM EDT
[#42]
Quote HistoryQuoted:
Here is the blaster that got the above treatment. Just waiting on the Q Cherry Bomb to come into stock at RSR or Lipseys and then toss the optic on with the Geissele 1.93" T2 Mount. Q Trash Panda is also out of stock. Then maybe a M300. https://farm8.staticflickr.com/7894/31860766537_46d8722ac4_h.jpg |
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Posted: 1/20/2019 1:54:08 AM EDT
[#43]
Quote HistoryQuoted:
Dimpling, torque, and standard blue. It's worked so far. |
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Posted: 1/20/2019 6:17:19 PM EDT
[#44]
Quote HistoryQuoted: What are the specs on this? Upper: 1. BCM M4 Upper Receiver 2. Toolcraft Nitride BCG 3. SLR Non-adjustable gas block 4. Ballistic Advantage 8.0" 300 Blackout Barrel - Modern Series 5. Geissele MK8 7" 6. Geissele Airborne Charging Handle 7. BCM MLOK Grip Lower: 1. BCM Lower 2. LWRC Ultra Compact Stock 3. CMMG Ambi Selector 4. PWS Ratchet End plate 5. BCM Mod 3 Grip |
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Posted: 1/20/2019 6:24:58 PM EDT
[#45]
Standard 242 blue is only good to 300*
246 ------------------------450 2422 -----------------------650 All are medium strength |
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Posted: 1/20/2019 8:02:52 PM EDT
[#46]
Quote HistoryQuoted: The basics setup is this ... Upper: 1. BCM M4 Upper Receiver 2. Toolcraft Nitride BCG 3. SLR Non-adjustable gas block 4. Ballistic Advantage 8.0" 300 Blackout Barrel - Modern Series 5. Geissele MK8 7" 6. Geissele Airborne Charging Handle 7. BCM MLOK Grip Lower: 1. BCM Lower 2. LWRC Ultra Compact Stock 3. CMMG Ambi Selector 4. PWS Ratchet End plate 5. BCM Mod 3 Grip |
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Posted: 1/20/2019 11:44:06 PM EDT
[#47]
Quote HistoryQuoted: Real clean on the rail to barrel ratio. Did you still have the barrel pinned...how you like the SLR? |
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Posted: 1/21/2019 1:49:18 AM EDT
[#48]
Quote HistoryQuoted: Yes the gas block is pinned to the barrel and set screwed as well. SLR is top notch. I use BRD Engineering Jigs for dimpling and pinning. I have a spare Geissele block but dislike the chrome color. I would want to pin that as well for kicks. Or I may just get everything from SLR to make it easy and add a second dimple to the Rosco Mfg barrel. For some reason they only dimple closest to the journal shoulder... |
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Posted: 1/21/2019 11:09:21 AM EDT
[#49]
Quote HistoryQuoted: Thanks for the additional info, I'm currently looking to see what jig(s) & gas block I need on a 300BLK build. I have a spare Geissele block but dislike the chrome color. I would want to pin that as well for kicks. Or I may just get everything from SLR to make it easy and add a second dimple to the Rosco Mfg barrel. For some reason they only dimple closest to the journal shoulder... Please correct me if I am wrong, but there is no "MILSPEC" spacing for the set screw centers. |
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Posted: 1/21/2019 12:21:14 PM EDT
[#50]
Quote HistoryQuoted: They only dimple the one because that is the only one that will always be in the same place. The center to center set screw spacing is different for almost all of the manufactures. I like the SLR .400" so that is what I get. Please correct me if I am wrong, but there is no "MILSPEC" spacing for the set screw centers.  Attached File Attached FileIssued barrels with dimples  Attached FileCD |
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