“You have to pin the gas block or else!” say a lot of serious AR-15 builders, the “or else” being that the block will work loose and your rifle will malfunction. Nowadays, there are gas blocks that clamp on or are secured by setscrews, so we asked Brownells Gun Techs™ Steve and Caleb if pinning is absolutely necessary. The original AR-15 / M16 design called for the gas block to be pinned, and that’s still the most SECURE, most durable method. But the other attachment methods make it a lot easier to install or change the gas block. If you want a pinned gas block and don’t want to do machining, you have to buy a barrel with the gas block already installed. Setscrew and clamp-on gas blocks are great for the home “hobbyist” AR-15 builder, especially low-profile gas blocks that will be protected by the handguard. If you’re like Caleb and want your AR-15 to last through the Apocalypse, pinning is the way to go. The Smyth Busters are split on this one: Steve says the gas block doesn’t always have to be pinned, Caleb says it does. What do YOU think? Tell us in the comments below!
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I do feel inclined to pin the gas block. That said, I bought a gas block that was already drilled for a pin, but came with a splined pin instead of a tapered one. No instructions of course, so I'm at a loss. Tempted to just drill it out with the #31 and a #2/0 taper reamer. Their site does mention to use a 1/8" drill bit and press, which is just slightly bigger than the #31. So I fear that if I try it that way and hammer in that splined pin, I may not be able to change my mind.
I prefer the pinned method because if you shoot enough your gas block will vibrate loose
You can absolutely buy a gas block with a hole in it install it on your barrel and drill that section of the barrel out that’s exactly what you do with SOLGW barrels
Great video
Depending on the barrel…..Dimple and pin… You don't have to taper pin…..3/32 with a quality coil is more than sufficient…..I do believe a forward assist Mil-Sec is the correct size with 3/32 straight hole…..5/32 taper….I've done them every single way depending on the build….
30 in lbs on the screws and rocksett.
After having been exposed to hundreds of dimpled and screwed gas bocks I have seen two come loose. Both were owned by the same person. Hmmmm. One was a 458 SOCOM and the other a 5.56 pistol. Knowing the person I would guess a lot of mag dumps out of them.
"How can you trust a man who wears both a belt and suspenders? The man can't even trust his own pants."
-Frank
I have a rock river arms elite operator bought in 2011 and sometime in 2017 after many range trips went to clean the rifle and the clamp gas block literally slid off. After that everything was pinned.
I'm a home builder who's been learning the gunsmith trade all my life and how I do it, I dimple the barrel and just use the set screws as opposed to pinning. Though I'm not military, my ARs get tossed around, worked, and abused to test how ruged they are after they're built and/or bought and I adjust accordingly. I've never felt a need to pin my gas block. If you're using a gas block with set screws and dimple the barrel. I found its sufficient enough to not come loose.
For greater peace of mind yes, but necessary? No.
Some of that expensive green bearing sleeve Loc Tite which is a step up from the red Loc Tite and that gas block ain't moving. I actually found an even stronger green thread locking compound but the cans are all labeled in Japanese Kanji. It's currently holding the trigger pin on a .40 S&W CZ75 in and I just put another 1000 rounds through that gun. Before I gooped it with that stuff that pin would have come out completely. That pin walks out just dry firing the gun. It's really loose, or it was. Now it's not moving, at all.
I personally don’t trust screws on guns unless they are safety wired. Why use a screw on a life saving device? Maybe for a precision AR.
I'd say if your block is exposed, pin it.
So I'm currently building one that's going to run about the same speed as a full auto. So with that being said should I just use a pin since this one is going to be hammerd on?
Anyone got a video of a clamp-on block failing?
Pinned!!
I like having them pinned if the option is there but I like set screws due to the ease of remove and modularity. I always dimple the barrel if not already dimpled. This is a must. I always replaces the set screws with Prime Line black oxide steel set screws. They are longer and have a deeper allen head pocket so they don't strip. Stainless steel set screws strip too easily. Threads and journal have to be thoroughly degreased for proper adhesion. Lastly, I install them with Rocksett and torque them to 30 in-lbs. Prefer Rocksett because of its strength and it won't melt or loosen with heat. I have yet to have a gas block or any set screw come loose during any hard use, suppressed or unsuppressed.
After putting in my gas block and tube will my barrel nut help to ensure that the tube to bcg alignment is centered ?? because without it on yet, the gas tube goes towards on side of the upper and isn't perfectly centered.
Great stuff
Pin it
What about dimpled set screw, that you stake after torqueing?
I really want to see your new red suspenders
"It's under the handguard and protected so it doesn't need to be pinned." Is only true if never plan on shooting it. Therefore it's false. Vibration loosens set screws. Heat defeats loctite. Maybe if the barrel is aggressively dimpled and the set screws are staked. Otherwise if the gas block is not pinned it is nothing more than a range toy. You can disagree but you'll be wrong.
One of these days, Steve isn't gonna let Caleb off so easy.
i just j.b. weld it on
Pinned gives better night sleep.
I have one for you. Really been bothering me lately while reading comments. The assertion that loading below minimum charge will likely lead to a bore obstruction and the next round will blow the gun up.
Now I'll admit that a barrel obstruction is serious and theoretically a light enough charge won't even get the round out of the barrel. That said, it's my understanding that the minimum load data published for specific bullets has more to do with achieving enough velocity to stabilize that bullet. Am I completely wrong? Does a 35gn bullet out of a 22-250 go from a muzzle velocity of 4,000fps to 0fps when you go 0.1gn less powder?…. The ONLY actual incidents I've heard of with reloads leading to a barrel obstruction have been from failing to put ANY powder in and only the primer firing. I would love for someone to test just how little powder is needed before the bullet doesn't exit the barrel.
The main difference between the pinned and un pinned gas blocks is that bayonet lug.
That lug is the anchor for the pokey thing.
No alignment pins and you risk tweaking or outright disassembling your gas system when using and or removing the bayonet.
Also forgot that the A frame for the front sight is pretty important as well.
I personally don't want that held on to hot barrel with set screws.
I recently modified my m&p15. Went with black and fde. The gas block and tube were a real b*tch to do, probably spent majority of the time just pinning it! but it was a fun build all in all
A dimpling fixture and two set screws are virtually as robust as a pinned gas block. The only way to absolutely validate one over the other is to have a shoot to failure comparison test. I think that would be prohibitively expensive for the differences. If you are shooting full auto there might be a reason to pin the block but so many competition guns, run hard and seem to validate the reliability of a dimpled and setscrew installation. JMHO.
Eugene Stoner was a damned genius. One thing You will notice about the AR-15 is the absence of allot of screws. There is essentially 3 screws on the whole rifle. Two on the gas key and the other holding on the pistol grip. One can't help but think if Stoner had access to modern machine tooling and cnc machine tool paths He would have machined the gas key into the BCG. Screws suck on any machine as they introduce a failure point.
let me ask a question if you pin your gas block, is that pin location specific to 1 particular gas block, or do all gas blocks have the same pin location, on all barrels? and the same question goes for dimpling a barrel for a gas block? do all gas block have the same lock screw location? so if I were to dimple my barrel and decide that I want to use a different Gas block from a different manufacturer, are the dimples in my barrel still going to work, or am I going to have to make modifications to the dimples?