Ways to align a gas block

[FLshooter]

[rabiddawg]

Same as you

[A5BLASTER]

Insert the charging handle/bcg, flip the upper upside down and slide the gas tube/gas block assembly in till the tube hits bottom, then flip over and make sure the top of the block is straight inline with the gas tube port in the upper reciver.

Works 100% of the time.

[BluntForceTrauma]

[FLshooter]

[Mesa1978]

"Blowing on the barrel" has always worked for me through over a dozen assemblies of ARs to verify gas block alignment

[centerfire]

[GregP42]

Piece of spaghetti noodle in port, slide block on, turn over and look down barrel, noodle will drop in when it is aligned, then flip back, run rod through barrel break noodle, pull rod back and let other part fall in then push it out too.

Greg

[rebby]

If I'm using one of the newer Wojtek gas blocks, I'll just eye ball it. That's kind-of cheating though since they're drilled with a witness hole.

For a "more traditional" gas block, I've tried a number of techniques and have had success with all of them. On some, I'll just eyeball the center line of the barrel, run the block to the shoulder, back off a "touch", and clamp it down. I've never had a problem doing this but I don't make a standard practice out of this method either, quite honestly, I'm too anal and "close enough" just isn't close enough. Since every barrel and gas block is somewhat unique, here is my normal process;

• Mark the center line of the barrel using the barrel extension indexing pin and the gas port with an ultra-fine tip Sharpie about 1/4" on the chamber side of the gas block shoulder.
• -- Assemble barrel / upper --
• Take a measurement from the chamber side gas block shoulder to the edge of the gas port.
• Take a measurement of the approximate size of the gas port in the barrel (or check the spec sheet, I don't like sticking metal calipers in the port so close is good enough, within a few thousandths).
• Take a measurement from the chamber side of the gas block edge to the edge of the gas port.
• Take a measurement of the gas port in the gas block.
• Do a little math using the above values to figure out the ideal spacing between the edge of the gas block and the shoulder so that the gas ports are stacked on center.
• Install gas block and use feeler gauges to set the final position. The above measurements will let me know exactly how precise I need to be. I also assure that the gas block installs vertically on the center line based on the index line that I drew earlier, dimples/flat will help when using set screw blocks.
• Confirm proper gas key engagement prior to torquing things down.

I kind of miss the days of A2 FSBs with factory positioned/drilled taper pins sometimes.

[rebby]

Piece of spaghetti noodle in port, slide block on, turn over and look down barrel, noodle will drop in when it is aligned, then flip back, run rod through barrel break noodle, pull rod back and let other part fall in then push it out too.

Greg

Smart man's UniqueTek

[joedirt199]

After using the wojtek style, I drill a hole through the gas block for a witness. Drop a proper drill bit in the gas port hole and line the gas block so the drill bit is straight up. No issues.

[FRB6.5]

Another method to verify alignment has come about with the proliferation of cheap bore scopes. Is very easy to look directly into the gas port and see if there is occlusion or not.

[sundog]

Piece of spaghetti noodle in port, slide block on, turn over and look down barrel, noodle will drop in when it is aligned, then flip back, run rod through barrel break noodle, pull rod back and let other part fall in then push it out too.

Greg

Same thing except I use a piece of toothpick.

[ARErector]

A lot of great ideas. I have usually just eyeballed them and didn't have a problem. Most recently I've been blowing down the barrel and also eyeballing it so it also looks straight and has proper gas key alignment. I've wanted to try the spaghetti or toothpick trick, but I just keep doing the blow thing when the time comes. I don't think I've ever had an issue.

[Lastrites]

Just about as many ways to break in a barrel, lol. I generally remove the set screw that is inline with the gas blocks inner port, install it upside down to get the distance if any off the barrel shoulder and find the proper feeler gauge that fits. Mark the center of the shoulder and mark the gas block to align them and use insert feeler gauge and screw it down.