AR15 not ejecting

[goofygrin]

Built a bit of a franken AR.
PSA lower and LPK
Mega upper with a 20" 1:7 CL barrel (bought used)
Rifle length gas system
MOE collapsible stock
carbine buffer (2.9oz)

Using (cheap, HP, what I had on hand) Hertgers/Tula 62g .223 ammo, every single one of them wouldn't eject. It wasn't typically jamming a new round in, so it's like a super short stroke. Pulling the charging handle would extract the spent case and load a new one in from the mag.

On the last round in a mag, it wouldn't hold the bolt open (or eject the spent round).

Could the ammo really be that underpowered? Or is it possible that my gas block has gotten knocked over a bit?

I think the easiest next step is to clean things up and try some better ammo, but if there's something else I should try I'm all ears.

[Downs]

What buffer and recoil spring are you using? Shouldn't be an issue using the Herters or Wolf or anything else as long as everything is working properly.

Edit- I see you are using a carbine buffer on a Rifle length gas system. Try using a regular rifle buffer and spring and see if that helps. Usually the carbine buffers are heavier and the springs stiffer to account for the more violent carbine and mid length gas systems.

[goofygrin]

carbine buffer, and I'm assuming carbine spring. I measured it and it's about 11.5". Fairly stiff, I was thinking of going to CTD tomorrow and seeing if I can get a softer one.

[KBScobravert]

Plug barrel at either end, put a nozzle from a can of compressed air in the gas tube, send air through and feel for volume in the barrel at your open end. Any variation of that will let you know if you are having a miss-aligned gas block.

Are you using a rifle or carbine buffer tube?

If your rifle gas is not pushing the carbine buffer system try to trim the spring s coil at a time until it functions.

My guess is a combination of all the above. JP Enterprise will tell you that nearly every factory DI AR is OVER GASSED. Their recommendation is to close the gas port and open it as needed UNTIL the gun functions, then use that configuration. Of course those guys are shooting tuned hand loads but the theory holds true just ensure you can compensate for ammo variables.

You sour be shocked at how soft a rifle gas system will recoil and still cycle the bolt.

edit: I just saw collapsible stock. Still folks the above. You may need to tune the buffer and spring.
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[Downs]

My first suggestion is to go to a rifle buffer and spring especially with a 20 inch barrel and rifle length gas system.

Test and see if that'll make it run better.

[goofygrin]

I was able to plug the chamber with a spent case and I blew through the muzzle and air came through the gas tube. Not sure how hard I should have to blow. Wasn't hard, but wasn't like blowing bubbles in a soda.

[KBScobravert]

My first suggestion is to go to a rifle buffer and spring especially with a 20 inch barrel and rifle length gas system.

Test and see if that'll make it run better.

Rifle buffer wont work in a carbine buffer tube. Too long unless you used a spring closer to 6" .



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[goofygrin]

My first suggestion is to go to a rifle buffer and spring especially with a 20 inch barrel and rifle length gas system.

Test and see if that'll make it run better.

This means a rifle buffer tube too which means a fixed stock or expensive A5 stock....

[CJ]

I'd check that gas block alignment personally.

[1985gt]

gas system length and buffer/spring are not related. you can run a carbine buffer and spring on a rifle length gas system and vice versa. If you have a carbine buffer, you need a carbine buffer spring - If you have a rifle buffer, you need a rifle buffer spring. One is lighter with a stronger spring, and one is heavier with a lighter spring. They even out to the same thing except for the length of the buffer.

shoot differnent ammo before you change anything.

[Jeremycg777]

Man anytime I used Hertgers I had to make sure my ar was really clean or i would end up with a failure to extract or end up with a case stuck in the chamber and the extract ripping a piece of the rim casing off

[GSXRK5]

I have a 24in with a carbine buffer and my ejects shells ok.

[Downs]

I wouldn't have a rifle that won't run steel cased ammo. I want my shit to run on anything. Generally if it won't run steel cased stuff reliably there's some issue with the gun outside of the ammo.

Mine used to choke on Wolf and Brown Bear. I found a weak extractor spring and replaced the extractor (failure to extract with Wolf)and a weak hammer spring (failure to fire with brown bear).

After fixing the issues I've ran 2000 trouble free rounds of Wolf and Brown bear at classes with no problems.


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[goofygrin]

I'd check that gas block alignment personally.

My front sight looks like it uses hex screws not roll pins. Is this a normal occurrence? They are very small (1.5mm maybe).

How do I fully check the alignment?

[KBScobravert]

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