Brownells Gun Tech™ Caleb Savant is here to set the record straight once and for all about AR-15 gas block alignment. Getting the gas block correctly aligned IS important, but it’s not as difficult or fiddly as you might think it is. Some folks insist that when you’re installing a gas block on a free-floating barrel, you should not push it tight against the barrel’s gas block shoulder. They say you should leave a small gap between the gas block and the shoulder so there’s room for the ring on a two-piece snap-on M4- or A2-type handguard. You should do this even when you’re not using that type of handguard because the gas block is actually DESIGNED to require the gap. If you don’t provide the gap, they say, the gas hole in the block won’t line up with the gas port in the barrel.
This is actually NOT TRUE for gas blocks on 5.56 / .223 AR-15s. The gas hole in the gas block is larger than the barrel’s gas port, so you don’t have to be OCD precise about lining up the holes. Caleb uses his handy borescope to show us what’s going on inside the barrel when he pushes the gas block right up against the shoulder of the barrel. Yep, the holes line up with no obstruction of the gas flow.
If the barrel you’re working with has a dimple for a gas block setscrew, go ahead and align the block based on the dimple. But if the barrel is not dimpled OR if you’re using a clamp-on gas block, it’s totally OK to run the gas block all the way up against the shoulder. The gas will still flow, and your AR will cycle. NOTE: This rule applies consistently only to AR-15s chambered in 5.56 NATO / .223 Remington.
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Gas block alignment can make or break a build, but there is more room for error than you think!
Yeah, you could push your gas block all the way to the shoulder, if you are a knuckle dragging Neanderthal.
Nice
That is the cleanest gas hole that I have ever seen; they usually have some kind of crap on them.
If your barrel didn't come from the factory with a dimple drilled for the gas block set screw, buy a dimpling jig and do it right. If that's too much effort or above your ability as a DIY gunsmif, perhaps you shouldn't be attempting to build an AR. If you have a clamp on gas block, why ?? Take it to a professional that knows what they are doing.
I wouldn’t call this alignment because without the bore scope it’s all guess work
….I used pencil marks on the barrel and gas block to align them and used a length of fish tank air hose attached to the gas tube to blow air intoit to ensure I had the hold aligned properly…BTW I noticed that the hole in the block was larger than the gas port in the barrel…
I was soooo stressed out about gas block alignment when I built my first ar. I must have done it right though, because It shoots perfectly. (And I did push it all the the way against the shoulder)
A trick a friend of mine showed me is put a spegitti noodle in the gas hole, knock the noodles flush with the top of the barrel. Install gas block, flip the barrel and let the noodle stop the gas block in place. Set your set screws and flip the barrel upright and knock the noodle out.
I use a piece of dry spaghetti noodle as a gas block alignment tool. I break off the spaghetti in in the gas port and the put the gas block on and turn the barrel upside down. The spaghetti falls into the gas block and locks the gas port hole with the gas block hole. Tighten everything down and turn the barrel right side up and use a cleaning rod to break the spaghetti and push it out of the barrel.
Awesome tip. I’ve always wondered how important that is
That is genuinely helpful information. Thank you.
It would be interesting to take 3 or 4 barrels and 3 or 4 common gas blocks and see if that standard applies across the board.
What brand/make is that barrel?
People who believe in leaving that gap are nothing but a bunch of gasholes.
I have used several of the Strike Industries indexable gas blocks on AR15's and LR-308's… perfect alignment every time as you visually line the ports up, due to how the are made and install.
When I have a problem with my gashole, I blame the dog. Love my borescope too.
Better yet just get a set screw gas block and a dimple jig and you'll be good to go then pin it too while you're at it.
Heh-heh, he said "gashole"
I'm just here for the "reeee!" responses.
Haha ah man had me laughing
Blow it out your gas hole, Caleb! 😂
Are AR-10's the same story?
Outstanding!
I had an upper that wouldn't run, pulled the GB, there was an off center burn mark in the inside of the GB. Shifted it forward 2mm, upper started working.
This video came at just the right time for me! I have a new .300 Blackout upper that wasn't ejecting the spent casing, so I took the handguard off and found that the gas block hadn't been locked down. I was wondering how far back I needed to set it, and your video answered my question. Thanks! 😊
I had always thought/assumed that, but it’s good to know for a fact!
I can't wait to link this video to so many misinformed people lol.
Muck'n gasshole
Awesome, thank you!!!
LOL, gas port. Much safer…
Very cool video! Thanks!
The easy way is blowing air down the muzzle and checking where the best flow comes through the tube where the gas key lines up
That's a very nice looking gashole you've got there. Surprisingly clean!
With the exception of Yankee Hill clamp ons that have the flip up front sight. It's really a good idea to get it aligned proper. And I tell you I have a barrel from another sporting goods store that if you slide the gas block back on it it does block the barrels gas hole enough to cause cycling issues. This brand suffered this alot in their earlier offerings. Reading the comments and ratings page shows that as there were a lot of people drilling them out lager on the barrels. I was and still am using a low profile block on that particular barrel. If I didn't space it I would have had to in large the gas hole on the barrels. Barrel shoots well..
What a bunch of gas holes man.