man that is good advice.

Damn good advice, thanks.

Wow that’s a great idea

Put one of those long cleaning q tips in the gas tube in the receiver, then with your thumb cover the chamber, blow compressed air and if the qtip flies out, you’re good to go.

@@juniyananajukyu dude does this help alot

2023 here. Haha. I also hear of blowing through the barrel with the barrel plugged at the end. When you feel/hear the most air going through the gas port you know you're spot on! I'll be doing both methods.

I agree. I'm just explaining how to set up offset from the shoulder if you want (sometimes it's necessary if it's a non-typical block or shoulder). It also gives one a visual way to see their tolerances too. I've found most gas blocks initially leak a little too until they get carbon and copper fouling in the gaps and then stop leaking. This is usually a mag or two of ammo before it clogs up.

Spot on Sean. By combining the above "left/right centering" using the penciled line and your "forward / rearward centering" technique you simply cant go wrong. As an added bonus, if you have feeler gauges , you can use them to fill the distance between shoulder and gas block (at whatever distance required) so when you rotate the gas block back to its normal position the feeler gauges keep that perfect "forward / rearward" distance.

When i watched i would have gone to my dial calipers,anyone who reloads has to be able to measure precisely.

Hi Sean,this was the best advice ever!.I slipped on a low profile gas block today and rotated it and it lined up perfect hard against the shoulder.What I would like to know is that good to go? Or should I allow .330mm where the hand Guard ring was?,I’m worried the gas tube will seat to far back even though the bolt closes fine.Or do they allow for that when manufactured.Its a Winham weaporny which had the pic a tiny type gas block on it,and going by the carbon stain it wasn’t perfectly centred on the hole either.

RSLewis ok thanks

I used the YHM-9384 gas block too, but I had to space the gas block .003" to align the gas block with the barrel. Check your barrel and gas block dimensions before installation. Not all are created equal.

Instead of using the Gas Port Line up kit being sold by Browells, Cut down a toothpick. Cut one end, then stick it in gas port in barrel. Spin it around while it's sticking in port and it will usually leave a mark. Cut it so it's flush with barrel. NOTE: Make it a semi-tight fit so it will move via it's own weight when barrel is rotated Remove it and clean up any burs, then position barrel with port in barrel facing UP. Put modified toothpick into port in barrel. Slide Gas Block on. Rotate barrel 180 degrees so barrel port is facing downwards. Tap, vibrate barrel a bit to make toothpick fall out of bore and slide into gas block. Rotate gas block to get a average of where center is. Tighten down gas block. Rotate barrel so gas port is UP..tap, hit barrel with hand so toothepick falls into bore. From chamber end... use AR clean rod without anything screwed into it... Slide it til it hits toothpick then give if a sharp rap. This will cut toothpick. Save the piece that comes out. Do same thing again. measure parts that come out. Compare to how long it was before cleaning rod sheared it into 2 pieces. Why use a toothpick / Vs a paperclip? Toothpick is made out of wood, is easily cut. TIP #1: To be on safe side, blow compressed air thru gas tube that mates with BCG to blow out any debris out of gas block and into bore of barrel. (Backflush) Blow out bore for good measure.. TIP #2: Measure the length of modified toothpick. Reason? Running clean rod down bore will cut into 2 pieces.. You want to make sure ALL of the toothpick gets removed. So.. Measure before and after, do TIP #1 .

Won't that paper clip damage the inside of your Barrel I know of two other methods that don't require you spending any money that work a lot better then pushing a paperclip metal Paperclip through the inside of your Barrel

One time use, but you get a pack of multiple. It's still a simple technique, but there are other ways.

Kevin Vellanoweth milspec will not sit against the shoulder because its ment to have that gap to make room for the delta ring

Use a toothpick

TheTdaddydog You are very welcome. Thank you for watching!

Khaosriged That depends on the gas block and the barrel. Sometimes a space is needed, other times it is not.

Trying to find out the same question.How do you know if gap is needed?,my holes line up perfectly centred if the new block is hard against the shoulder so should I set it at this? Or will the gas tube be back to far and damage the gas key?,the factory fitted block was slightly forward with the hand garud cap on there as you can see the carbon dot it has left behind so should I set it at that which is about .330mm ?,understand not all gas blocks are the same but would like to know how do you know if your gas tube is at correct length? Bolt closes with not restricted either way

Short stroking can be caused by many problems along the gas system. You should try a different bolt carrier to see if that helps. If not it can be a clocked gas block which is best to verify alignment with a bore scope. Then it could be a loose gas block to barrel journal, gas tube leak in the gas block, cracked gas block or cracked gas tube, out of spec gas tube button checked with a gas tube gauge, loose carrier key or an inefficient bolt carrier 3 bore..If all that checks out then your gas port is too small for the ammunition you are using...

You are thinking to hard and you risk getting that shit up in your tube.

No.

Phil, I'm neither. What I said is a true statement, and your lack of understanding about said subject shows you have nothing intelligent to add to the conversation. Don't believe me about the pencils destroying exhausts go ahead and draw a big circle on your headers and let me know how that works out for you. Hope you got a few bucks saved to replace them.

F*ckin' Sanders is correct . What I do is instead of writing on the barrel /gas block is to use tape.. put markings on tape.. then peel it off when done.

Jason Lees, lol found the aircraft mechanic. I came here to say that too.

@@soconnoriv, Hahaha, it's funny that we aircraft mechanics (former USAF Crew Chief) noticed that particular issue with his video.

aircraft mechanic also checking in for this comment, no graphite!

You're welcome :)

There can be a gap between the barrel journal shoulder and gas port depending on if the barrel was cut for a hand guard cap..

lkazanov Thanks! It works pretty good :)

+Shon Thurman You are welcome ☺️

soconnoriv what would you recommend using instead?

Brandon Spears chalk or grease pen would be better. Preferably chalk

There should be a very slight gap between the shoulder of the Barrel in the gas block if you did not leave the space keep in mind that the hole in the gas block is bigger than the hole in the gas port on the barrel so it allows for a slight difference

Not all, but most.

+ChanChan3255 I am not sure what you are asking. Sorry.

+nsz85 I had thought that there would be some small piece of the gas block that would fit into the opening in the barrel (or vise-versa) in order to ensure that the two holes are lined up with each other. But it looks like it is possible to have the gas block secured to the barrel without being properly aligned with the gas port. So basically, when you install you a new gas block, do you have to fire/cycle the gun in order to be %100 sure that the gas block is correctly installed?

+ChanChan3255 You need to make sure it is aligned. There is some wiggle room as the hole in the gas block is typically larger than the gas port in the barrel. If you watch this video and do what I did, you will have it aligned properly.

+Jake T. Best advise, don't do it. If you cannot find one that fits correctly, you will have to ream it out with a piston reamer. BTDTGTTS. What a pain in the ass. You are best off taking it to a shop that specializes in ARs and getting some assistance.

+Marshall Jones-Paragon Fury It depends on where the gas port location is on the gas block. You have to figure that out. Some do not require a gap but some do.

and yes, first AR. decided to build it instead of buy it.

Surviving65 ... did it work placed all the way back ?

Get a low profile gas block. And yes a .750 is standard the smaller size is for thin profile barrels. Good luck!

Thanks I had the same question and you answered it, Thanks

Staking can help and regular blue locktite will burn off.. There is a product called Flexbar Rocksett which is a high temp thread locker than will withstand 2,000 degrees F.

+Khaosriged Not always, see my stand alone post from today on how to check.

+Khaosriged ... +Sean M is correct. I previously had the same concern with spacing. On a related topic -- and Sean M can correct me if I'm wrong -- but it's also fairly simple to line up the gas block/gas tube simply by installing it. After installing your barrel, torquing your barrel nut and sliding the gas tube (that's already attached to your gas block) into the upper receiver, you're pretty much lined up. After that, tighten down your gas block set screws while making sure you're not twisting the gas tube. I have used this method for a couple of years when building ARs and have had no problems. Just my two cents.

He does but it takes 15 seconds to measure the opening in the barrel and block to double check. If they don't line up, well, now you have the maths to get it right.

@@AtomicCitizen He aligned them but "did no"t measure the gas block port to the end of the block and compare it to the measurement of the barrel port to the journal shoulder.If the barrel journal was cut for a hand guard cap then his ports would not be aligned..This video is 8 years old and was cutting edge info for the time...

www.midwayusa.com/product/462151/yankee-hill-machine-gas-block-low-profile-clamp-on-ar-15-lr-308-standard-barrel-0750-inside-diameter-steel-matte

Sure thing!

+djalkaline1 Not really. Even if its supposed to be there and you butt up the gas block, you still hardly ever impede gas flow. This is for all the major brands that make low profile gas blocks. There are some exceptions out there in both block and barrel, but figuring out if it's needed is fairly simple.

.750 should be your barrel diameter. Not the size of port. To not waste your money verify your barrel diameter, and purchase the correct gas block.

+Erick Nieman right! easily confused here. thanks!

+Justin Pooley No problem

Yes and nobody realizes this you were the first of many comments

@@crypto_pinto2660 except that's not always the case

@@indicastrain4127 it's been a question of mine for almost a month now and every video I've watched nobody's mentioned that Gap whether it needs to be there or doesn't need to be there but I did get my answer finally some barrels allow for some viral don't some barrels have a big enough gas port on the gas block to where you can add an end cap or you don't have to. But basically you are correct

@@crypto_pinto2660 A gentleman who commented on this same video pointed out that if you remember the hole in the gas block and one of the set screw holes are drilled at the same time... and if you rotate the gas block 180°, you will see that set screw hole in relation to the gas port, then you can better determine how far off the shoulder (if any) you need to be. His name is Sean M. I believe

@@indicastrain4127 I saw the video that's how I figured it out. Also the hole in the gas block itself is made a little bit bigger than the Gasport on the barrel for the reason of either placing an end cap or not. That's my understanding anyways so far I have no gas issues on my rifles both with end caps and free float tubes. My BCG Cycles perfectly so far

+mclerj 057 You are welcome :)

+Ryan Jones It would not eject.

That is the general rule but there are exceptions.

He could have measured the gas block and gas port to barrel journal shoulder to verify..

taurran Sure thing. I am happy to help.

+saleenr6 If your gas port in your barrel isn't exactly on top, your barrel is suspect for mechanical issues. More than likely it has come loose from the barrel extension and you are headed for serious bad ju-ju. If this is the case have it checked by a gunsmith or armorer at an AR specialist store. If the port is completely vertical, you should have a +/- 5 degrees to install the block and not impede the gas port flow. This is also dependent on the actual gas port diameter, but it's a good rule of thumb.

Idontcare_626 Yes. Yes I did.

nsz85 in the video your gas block hits to the end. You did not place 2 business cards to compensate for the handguard.

JMazterV112 In short yes, I had made the mistake of not double checking the gas tube. I set the pin and I experienced FTE there was not enough blow back pressure due to the hole being half covered and the gas tube wasn't fully going all the way into the bolt carrier group. So literally after every shot the bolt carrier wouldn't eject the shell I'd have to pull the hammer again as if it was a revolver

Surge I had this happen to me too!! My rifle thankfully I had it fixed but incredible how one has to make sure these are crucially inspected

JMazterV112 I fixed it myself and it shoots like a charm now. Turns out the gas tube had misaligned holes so it was lined up perfectly with the pin but the hole where the pressure from the bullet blows back the bolt carrier was cut off half so I drilled out the hole bigger and now it works perfectly

JMazterV112 remember, the hole in the block is considerably larger than the gas port hole so that allowed for minor misalignment with full gas flow. Use this method to confirm left to right adjustment. If you confirm the inset distance to the center of the port on the block from the edge of the gas block, and do the same on the barrel you can confirm barrel to chamber assignment. Then you should be good to go.