Build Help - Cycling Issue

[bullterrier391]

Shanner,

"A quarter of the width" (of the barrel at the gas port) is 1/4 of 3/4" - yes? That is way more than the width of a credit card, which is what I thought it might be because of Old Bob's explanation in Post#9. Forget that theory - Sounds like you've got a gas block with set screw holes that are just way out of alignment with the dimple in the barrel.

Regardless, you do have to pull it apart and measure the distance from the barrel's shoulder to centre of the hole, and then the edge of the gas block to the centre of the hole. If they are the same then you can push that block right up against the shoulder with confidence and only then have to worry about rotating the block until the holes exactly align. For that you can scratch tiny alignment marks on the shoulder and block to line it up perfectly. Even just slightly out and it's going to choke the gas like it's a smaller hole.

With respect to 'Bullterrier' you won't need a pin set to do this (I don't have one). A set of calipers will do. You can also measure the port size with calipers.

Lining up the gas holes for maximum efficiency is a thread or two on this forum if you want to search. Some guys use bore scopes which means you have to have access to one. Another method is using a toothpick in the gas block. When it is in alignment gravity lets it drop down into the barrel where you crack it out with a cleaning rod. Or you can buy the plastic version of this from HB industries https://www.youtube.com/watch?v=V4f9stp4SWE. I have never used these methods but no doubt they work.

I have just marked and carefully measured with calipers - but whatever method you use you do have to line those holes up exactly, especially in a caliber or gas system that is not as generous with gas as others. If the dimple is misaligned then screwing it tight is going to pull it out of alignment. One solution for this is to replace it with a clamping gas block, which is arguably a more efficient seal anyway. But for that you have to buy a new block. If the dimple is pulling your block out of alignment as you do it up there's not much you can do to fix that. Drill a new hole and screw onto an un-dimpled part of the barrel maybe. That's if there is enough length of block to do this - It's a bit of effort for the sake of simply buying a new clamping block. Up to you and how much money you have.

If you cannot line up the holes without the dimple pulling the block out of alignment then a clamping block is what I would do. As long as it doesn't make contact with the inside of the handguard to keep it free-floating.

That is of course if the problem is the gas holes out of alignment, but it won't hurt or cost to pull it apart and carefully measure, as they say in the emerald isle - 'To be sure, to be sure'.

Klem, spot on advise. I would and have used all of it. have a teslong bore scope and had a buddy make me a fiber optic light to run down gas tube to verify everything lined up. I have had three 223 wylde builds that drove me crazy. block ports dimple all gtg buffer gtg spring gtg gas key and tube gtg. and still weak. also had access to a pin gauge sets from work. I can't remember off hand but sets went up like .061 .062 .063 etc just took port up in one increment at a time and boom cycle like a champ. should have logged info in notebook, but once cycle great left them alone after. all I have ever used is ba barrels except one was areo. think ba makes them for areo not sure. this has been my experience with cycling issues each time. just built my first Grendel with a ba Hanson barrel and did not check port upon assembly.I have not tested it yet, but I have an issue that would be my first look. this site is great tons of good info and experience here. happy building/happy shooting !!! My experience is novice at best so don't mean to offend anyone.