AR-15 build will not cycle. Need help/advice

[Varminterror]

Ah, c’mon - who here wasn’t at least a LITTLE excited at the prospect of the OP crashing the far side of his bore with the port reamer?

 

[MistWolf]

And preferably with a reamer, not a drill bit.

Definitely!

 

[mookiie]

Dont have a reamer, and what would be the "correct" size holes?.

 

[mookiie]

@Jackel I might try that. I do have a buffer kit I could use as well as wood replacements for the weight. Trouble is I do not have a quick/easy way to verify/test to get the buffer weight, but the same arguement could be made for drilling out the gas port...

 

[Wreck-n-Crew]

Gas port size chart found here and elsewhere. https://www.m4carbine.net/showthread.php?41592-Gas-port-sizes

Edit to add: If you open it to a larger size you can use the adjustable gas block to compensate for over gassed system if necessary. Chart says .070-.086.

 

[MistWolf]

@Jackel I might try that. I do have a buffer kit I could use as well as wood replacements for the weight. Trouble is I do not have a quick/easy way to verify/test to get the buffer weight, but the same arguement could be made for drilling out the gas port...

Let's not get ahead of ourselves. Until a lock back check is performed, you have no idea what the problem is or how it should be corrected. Without a lock back check, you don't have a baseline with which to compare how anything you do effects the rifle. You'll be working blind.

 

[Varminterror]

@Jackel I might try that. I do have a buffer kit I could use as well as wood replacements for the weight. Trouble is I do not have a quick/easy way to verify/test to get the buffer weight, but the same arguement could be made for drilling out the gas port...

If you haven't done all of the troubleshooting steps I listed here, then jacking around with weights or reaming the port is just a fool's errand.

 

[mookiie]

Quick update guys:
1) Removed gas block
2) Verified no debris
3) Measured whole to be .89
4) Drilled it out carefully with a .96 sized bit based on barrel length, and gas system length, from resources provided above.
5) Test fired perfectly.

Thanks a lot guys this one has been to and fro on the last 4 range sessions, now at least I know she will run when I take her out.

Again Thanks!

If anyone has a similar resource for AR pistol gas systems I would really appreciate that as well, I have a .223 and .300 AAC build in line next.

 

[Wreck-n-Crew]

Quick update guys:
1) Removed gas block
2) Verified no debris
3) Measured whole to be .89
4) Drilled it out carefully with a .96 sized bit based on barrel length, and gas system length, from resources provided above.
5) Test fired perfectly.

Thanks a lot guys this one has been to and fro on the last 4 range sessions, now at least I know she will run when I take her out.

Again Thanks!

If anyone has a similar resource for AR pistol gas systems I would really appreciate that as well, I have a .223 and .300 AAC build in line next.

Glad you figured it out.