18" rifle gas SPR build not locking back/cycling.

[mk3mark]

Specs:
---------
-18" Rifle gas ODIN Works DMR barrel 223 wylde
-SLR sentry 7 gasblock(Also used the supplied ODIN non adj.)
-FA BCG from Aimsurplus.com
-Aero Precision Upper
-A2 stock with factory guts from operationparts.com(Also tried carbine tube with both H and Carbine buffers)
-Griffin Armament Brake. (Not that it matters)

Ammo used was Tul, Wolf, and AE xm855

Long story short, the first range trip was with the a2 stock and non adjustable block. The rifle would not lock and and either FTE and induce itself into a stuck spent shell and half stripped live round. Manually cycling the rounds, it ejects fine and strips rounds fine. I know Tul and Wolf are low powered, inconsistent loads but I've seen many rifle length builds eat it up fine.

I went ahead and tried the SLR block on all setting's to no avail with both the a2 and carbine setups. It locked backed once using a pmag 20 with one round on AE 556.

The gun is just being inconsistent. It either fails to eject the round (it stays in the chamber) or it ejects and doesn't feed a new round, or like said above a little of both. I'm truly stumped. I have also removed the gas block and checked for straightness and the gas ring was perfect over the gas port.

Odin on facebook was real helpful and told me to call them and talk to Justin or John but they have yet to call me back.

[Onyx Z]

First off, try a different mag. And being a 3-gun barrel, I bet the gas port is smaller than spec. Those things run on the cusp on not cycling. Try to get a measurement on the port with some mics.

[lrc]

I recently repaired 2 18" uppers for someone with same symptoms. They were 18" midlength Wilson barrels with troy gas blocks pushed up tight against the shoulder on the barrel...I slid the gas blocks back toward the muzzle .030 about the thickness of a standard handguard cap which centered the gas block port over the barrel port and that took care of the issue.

[BufordTJustice]

This is a gas drive issue. Check your carrier key and your gas rings on your bolt. My Rainier 18" with rifle gas would run a Vltor A5H4 buffer with a Springco green when I used as non adjustable gas block.

[incognito]

... And being a 3-gun barrel, I bet the gas port is smaller than spec. Those things run on the cusp on not cycling. Try to get a measurement on the port with some mics.

Agreed.

[Iraqgunz]

Use a set of pin gages. A good port size would be .0995. I would also make sure to check that gas block alignment as I am seeing a lot of this with barrels not being dimpled and the blocks being seated to the rear.

[Clint]

Yeah, check the gas port size.

The 18" rifle is a good configuration and should run.

[mk3mark]

I recently repaired 2 18" uppers for someone with same symptoms. They were 18" midlength Wilson barrels with troy gas blocks pushed up tight against the shoulder on the barrel...I slid the gas blocks back toward the muzzle .030 about the thickness of a standard handguard cap which centered the gas block port over the barrel port and that took care of the issue.

I've read this, as Wilson barrel's are to be used with an a2 front sight / handgaurd cap setup. I've checked it anyways and it's spot on.

You've made the investment in good parts and (assuming) a good build. Don't feed the weapon shit ammo.

If it doesn't eat everything, it's useless to me.

This is a gas drive issue. Check your carrier key and your gas rings on your bolt. My Rainier 18" with rifle gas would run a Vltor A5H4 buffer with a Springco green when I used as non adjustable gas block.

I've checked once, and haven't found anything loose, leaking or canted. No binding either. I replaced the gas ring's with a set from BCM for S&G's. They were a little screwy looking. Bent, if you will. If you sat them on the table they weren't flat.

First off, try a different mag. And being a 3-gun barrel, I bet the gas port is smaller than spec. Those things run on the cusp on not cycling. Try to get a measurement on the port with some mics.

I've tried a variety of different mags. Old faithful pmag 30's, mk2 tangodowns, brownell 30's etc. Also made a mistake and said it was their 3 gun barrel. It is the DMR barrel.

Thank you all for the tips. I pull the gun out and look it over every day, haha.

[Thump_rrr]

Is there any possibility that you broke the barrel locator pin?
I somehow managed to do that on a barrel and it wasn't till I removed the barrel that I discovered the problem.

[mk3mark]

Is there any possibility that you broke the barrel locator pin?
I somehow managed to do that on a barrel and it wasn't till I removed the barrel that I discovered the problem.

Nah, def not that. Alls lined up and solid.