Problem with my AR today

[JAGGUY]

So I got to the range today and took my AR carbine. Haven't shot it in a while but it was always good to go.
But today right from the start it was chambering a round but not cocking the hammer. It's never done that before. I have had some low power ammo cause a short stroke and not pick up a round but this was different.
It was doing this maybe 60% of the time and before I got 50 rounds through it started doubling... That's when I put it away.
At the time I was thinking low power ammo again but thinking about it now it did lock the bolt back when empty.

Now I'm thinking fire control problems... I don't have another trigger set right now but put up a wtb ad for a cheap set for a test.

Yes the carbine was clean and lubed.

Any thoughts on this?

[stevec223]

I'm no mechanic but how does your hammer spring look ??.. Are the legs in the right orientation to the sides??.. Dicso spring and trigger spring working and cleaned up and clear area ??.. Just my guess and curious myself...

[stix213]

With an empty mag, when you pull the charging handle, does it lock back?

Without a mag, when you pull the charging handle back and release, is the hammer cocked?

[SoCalXD]

If it is an 80% build lower, then the hammer pin holes are too far back, or trigger pocket was drilled to shallow.

Self Built rig, or is a brand name? if Frankinbuild, who's lower is it?

If it is ejecting the brass, then the bolt is going far enough back to re-cock the hammer, so it's not a gas issue. If it is doubling, then it's FCG, sear is not locking, and 2nd sear is not catching it on the first failure.

I would just remove the FCG, inspect everything closely, if good, then re-assemble it with precision and some grease. If it continues with the problem, swap out the FCG with a spare, then retest. if it continues, then toss that POS lower and get a new one.

[Sky_DiveR]

Do you mean the rifle was cleaned and lubed prior to putting it into storage or before you went to the range?
Was it working before you put it into storage?
What brand of lube do you use?

Take a look at your disconnector and spring. It may be gunked up from either carbon or old grease/oil. If you don't know how to disassemble your trigger, you can always watch you-tube or have a gunsmith/armorer take a look at it.

Good luck

Edit: Looks like the poster above me beat me to the punch. Also low-powered ammo would not cause it to double.

[JAGGUY]

Has a standard carbine spring and buffer.
I've had this a few years without any problems until today and in the past I would consider it over-gassed since it would run on anything including Wolf..
FCG seems to work when I manually work it but that's a lot different than when I fire it..
It's an LRB Arms lower with a generic lpk and the springs are in correctly..
I will take it apart tomorrow and look at the trigger parts and disconnector, there could be some crud in there.

Thanks for the thoughts!

[310Alex]

I have a Anderson manufacturer lower. I've been suspecting that my lower was not milled out right for a couple of reasons. Magazine catch seems to jam up. I've had misfeeds or double feeds at times. Swapped out aBCG and started shooting fine for about 8 rounds then it would not pick up a round when cycling from a previous fire. Any clues?

If it is an 80% build lower, then the hammer pin holes are too far back, or trigger pocket was drilled to shallow.

Self Built rig, or is a brand name? if Frankinbuild, who's lower is it?

If it is ejecting the brass, then the bolt is going far enough back to re-cock the hammer, so it's not a gas issue. If it is doubling, then it's FCG, sear is not locking, and 2nd sear is not catching it on the first failure.

I would just remove the FCG, inspect everything closely, if good, then re-assemble it with precision and some grease. If it continues with the problem, swap out the FCG with a spare, then retest. if it continues, then toss that POS lower and get a new one.

[310Alex]

Also when magazine is empty. Bolt catch does not keep the bolt cocked back

[JAGGUY]

Actually I always used CLP to lube AR's but today I used a little Mobile 1 for the first time. It wasn't as wet as using CLP but it seemed like there should have been enough?

[JAGGUY]

I have a Anderson manufacturer lower. I've been suspecting that my lower was not milled out right for a couple of reasons. Magazine catch seems to jam up. I've had misfeeds or double feeds at times. Swapped out aBCG and started shooting fine for about 8 rounds then it would not pick up a round when cycling from a previous fire. Any clues?

That sounds like under power ammo like Tula to me...

[310Alex]

I was thinking that also. I was using
Fiocchi 55gr 223 and ammo bros reloads in 223 55gr

[BarrettM99]

It is most likely two issues.

1. Disconnector Spring-it's cheap so just replace it.
2. Make sure the gas block is on solid. Inspect all screws and pins and make sure it's all g2g.

Hope you get her running perfect again.

[SmallShark]

if the bolt moved back enough to chamber a round, it should be able to cock the hammer..

my ar pistol failed to extract but still cocked the hammer

do an usual function check first

[emarkham]

JAGGUY:

Take the trigger apart and ensure the disconnector spring is installed correctly, wide end down and well-seated into the trigger trough.

[Rosamond]

Disconnector is the problem.