Overgassing Test

[Lonehill]

Is there anything wrong with test firing an AR with the gasblock and tube completely removed? Want to do this to bypass possible overgassing in order to see if my barrel is a shooter. Convinced that I'm overgassed and it's unlocking too soon and brass isn't allowed to grip the chamber properly. Shooting around 2 MOA @ 100. Pretty disappointed thus far. I can't see why it wouldn't work, just make it a single shot while troubleshooting.

[mongoosesnipe]

i wouldn't remove the gas block as leaving the vent open can be rather hazardous depending on the port location and the type of hand guard you are running damage or injury could occur

depending on what you have going on with your set up i would say just get an adjustable gas block for testing as you will probably need one any way

another solution which i have done is use a clamp on low profile gas block turned sideways in order to shut off the gas system and make an ar into a bolt gun

[Klem]

I wouldn't think it's a problem.

Having a tiny hole pointing to the sky is going to act similarly to all other ported muzzle devices. Just keep your fingers away from the port and your head in the usual position.

Reading on AR15.com there are a couple of posters who have tried it and one even had a handguard over it at the time. Claims the handguard got covered in carbon but did not otherwise damage it. Someone one else wrote it was difficult to work the action by hand afterwards but I doubt that. I have fired an Adams Arms piston with the gas switched off and there's no difference in effort working the action after firing a round.

[PigOPs]

I agree with mongoose... Just rotate your gas block enough to seal the port. I may have missed another thread but what have you done so far to troubleshoot? (Measured the gas port? What length barrel? Gas system? Buffer weight?)

[45r]

An adjustable gas block would let you turn the gas off and allow fine tuning once you get things worked out.
I might get SLR's new gas block.
It looks and works pretty good from what I've read.

[Lonehill]

Thanks for the replies, running a 18" mid-length gas system. Ejecting 1:30, brass kicking out 15 ft. Already running an H2 buffer and full mass M-16 type carrier. Haven't measured gas port. Running YHM clamp on gas-block. I like the idea of rotating it just far enough to seal the hole and leave off the tube. Can't see that it would hurt. Just want to quickly see if the damn thing will shoot well enough to justify spending $115 on an adjustable. Which is prob what I'll end up doing. At least I'll shoot a slow group, haha! It's not a headspace issue and I swapped out ejectors with another AR and it stopped chewing and stamping brass. Hoping it's just overgassed and hasn't had a chance to shoot to its potential.

[Klem]

I like the idea of rotating it just far enough to seal the hole and leave off the tube. Can't see that it would hurt...

Won't hurt it at all. The peak chamber pressure is well down by the time the bullet passes the gas port so sealing it off will give a slightly higher velocity but that's about it.

Using a clamping style block to seal the port will give a better seal than the older grub-nut designs that 'pull' the block from the opposite side to seal in one spot only.

[Dos Perros]

In tuning an adjustable gas block I started with it turned all the way down. Getting the charging handle to move back to eject the brass took a lot of effort. I had to beat on it with a tool before it would pop open.

[PigOPs]

In tuning an adjustable gas block I started with it turned all the way down. Getting the charging handle to move back to eject the brass took a lot of effort. I had to beat on it with a tool before it would pop open.

In theory it shouldn't take that much effort. However when all my parts were new I ran into the same issue and had to mortar it the first couple of times... Once my parts mated to one another I have found that I can turn off the gas and eject fired brass with very little effort.

[usmc1371]

Lone hill have you trued up the ten non where the extension goes. That can open your group up also.

[45r]

I put a set screw .750 bore adjustable gas block from battle tested equipment on my 18 inch ML gas liberty barrel and it works well.
Only 35 dollars and brass ejects perfect and will use AGB's from now on.
Rifle runs smoother and less powder residue to clean off BCG.
No early unlocking issues with the gas set just right.

[Lonehill]

Rotated the YHM clamp on block just enough to seal of the gas port, effectively shutting off the gas entirely and turning the rifle into a single shot. Recoil was significant even though .223 Wylde chambering, brass showed definite signs of over pressure. Cratered and even pierced primer. Brass flow. Very violent. Stopped immediately, waited on Syrac adjustable GB to come in. Tried that out. Started 6 turns open. Ran noticeably smoother/softer. Eight turns out, it started to nicely cycle and throwing brass in the normal AR 4 o'clock six ft out. Then encountered problems with the bolt not locking. Extracted the round and noticed scratches on the bullet, then noticed the crimping cannulure was no longer visible. Shooting factory Hornady 55 gr PSP. It's now apparent that I have a short chamber and the bullet is contacting the rifling. I then verified this using my Hornady Overall Length gauge and got a max length of a mere 2.10" @ rifling contact with a 55 gr V-Max which I plan on loading. I've never had this problem in any other AR. I usually load to 2.250" and wish I wasn't limited by mag length because I'm still way off the lands. Never thought to check for this using factory ammo. Headspace was previously verified with Go/No Go .223 Wylde but gonna check this again since I had removed the barrel to polish the feed ramps and then reinstalled and bedded with blue Loctite because the extension to receiver was loose even by Bangkok standards prior to this latest test. It is interesting to note though that my group size went from 2 MOA to 3/4 MOA. Guess I'll just load em short for this one and never worry about an eroding throat. Just can't run factory loads. Barrel is a Liberty by Satern, so no surprises with chamber issues there!

[NugginFutz]

Sorry to hear you got a stinker, Lonehill.

[rasp65]

It must need one of their special Wylde II chambers.