AR-15 FTF Issue

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AR-15 FTF Issue

Post by my pies are piff » Tue Aug 06, 2019 8:34 pm

Hi ZS. It's been a while since I posted, but I'm trying to get back into shooting and joined a club to get to the range more often.

I've been having an issue with one of my AR-15s. This is my SBR that is usually a safe queen. The other day my boss wanted to go out to sight in his hunting rifle for deer season, so I offered to take him out to my club so we could shoot a little instead of doing work. When we were shooting my AR it would eject the brass fine, but a new round wouldn't chamber. We had to pull the charging handle after every shot.

At first, I thought I had it in the safe too long without shooting and didn't oil it enough the night before. So I went home and oiled it pretty good. I went back to the range today and had the same issue. The first trip I was only shooting with my PMags, but they all looked fine. I brought GI Mags out today and that didn't help. My next though is maybe the buffer spring needs to be replaced. I pulled it out and it looks fine. Do you guys think I should replace it or could something else be causing this issue? Pics are below. Thanks.

https://photos.app.goo.gl/i5T3T7qnhWPtKXCX9

https://photos.app.goo.gl/ottoFZEKi6DudjGw6

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Re: AR-15 FTF Issue

Post by boskone » Tue Aug 06, 2019 9:05 pm

Maybe try different ammo, and either clean the gas tube or adjust the gas plug open a bit (if adjustable)? Might be the ammo's either burning slow and not building enough pressure, or something's impeding the gas flow.

Maybe a lighter buffer spring (doubt it's worn out, that takes a lot of shooting) or lighter buffer counterweight?

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Re: AR-15 FTF Issue

Post by Stercutus » Wed Aug 07, 2019 6:45 am

Might just be the lighting but your bolt looks filthy. That will keep it from cycling properly.
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Re: AR-15 FTF Issue

Post by emclean » Wed Aug 07, 2019 7:15 am

I would think a worn out buffer spring would give you issues with it not going fully into battery, not problems picking up the next round.

as boskone mentioned, it could be ammo related, if it is a different ammo from before, or there maybe something impleading the amount to gas being delivered to the BCG. the only other 2 causes I can think one would be a burr slowing the buffer, or something similar dragging on the BCG during recoil.

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Re: AR-15 FTF Issue

Post by MacWa77ace » Wed Aug 07, 2019 9:41 am

Did it work correctly before?
Are you using 556 or 223 ammo?
Do you have a pistol length gas system? If yes, this may be your culprit. Short barrels with pistol length gas systems have issues. If you're using 223 switch to 556 but only if your chambered for multi, wylde, or 556.

When mag emptied did your BCG lock back? Test: load one round in a mag and fire.

MAG ISSUES:
How many mags did you try that that happened to you? Did it happen when using some mags and not others? If so could be a mag spring or mag seating issue on specific mags.
Did you store your mags with full 30 rnd loads for ext periods? Are your spings worn out? Test: Pull the spring and compare it to a new one and see if they are the same height/length.
And a mag not being seated all the way will do that every time. Even though the mag might not fall out if its resting on a bench or just snug. Test: after inserting pull on the mag without hitting the mag release. If it comes out, could be mag or latch.

BUFFER ISSUE
Not likely but if you have a rifle spring in a carbine, carbine spring in a pistol, and/or too heavy a buffer, that might keep the BCG from locking back. Test: compare that spring to another known spring or google the correct length of the spring for your tube and use a measuring tape. Check that buffer is to spec for your tube.

GAS ISSUES:
Piston or direct impingement?

Do you have an adjustable gas block on that? open it up a little. Or make sure the GB is not clogged. If the bolt isn't getting driven back far enough it won't pick up the next round but may still eject the spent round.
Is the Gas Block itself loose? It could also be a miss match between the gas port and your gas block. Make sure your port aligns with the block.

Make sure your gas key is not cracked or loose.

Make sure your bolt's gas rings are good, I keep the spaces at 12, 4, and 7 o'clock to make sure that they are not in a line. Test: remove the BCG, pull the bolt head full forward, and stand the assembly upright on the bolt head. If the bolt head supports the bolt carrier without it sliding down, your gas rings are good. If not, replace them.
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Re: AR-15 FTF Issue

Post by my pies are piff » Wed Aug 07, 2019 2:40 pm

Thanks for all of the suggestions guys. Here are answers to some of the questions:

I never had issues with this rifle before.

I tried 3 different P Mags and 2 GI Mags

I was using 223 the last couple of trips. I'm thinking it may be the ammo since I was shooting up some reman ammo from Freedom Munitions these last 2 trips. I never had issues shooting other 223 or 556 ammo. I'll take it back out to the range with some XM193 and report back.

Here is a pic of the AR. It's my SBR. If I keep having issues after switching ammo, I'll try to using another BCG from my other AR in this one.
https://photos.app.goo.gl/8LBUptqRog51uM5z7

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Re: AR-15 FTF Issue

Post by MacWa77ace » Wed Aug 07, 2019 4:00 pm

I heard things about Freedom and know a sponsored user dropped them due to FTE's.

Did the bolt lock back when you fired the last round in a mag, that's important info. If it doesn't it could be an undergassing issue if its not a mag issue.

556 is more potent than 223 so it could fix an undergas temporarily but if it was working before with 223 i think something changed in the system. I'd check the rings at the very least. Alignment and gas test.
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Re: AR-15 FTF Issue

Post by 91Eunozs » Wed Aug 14, 2019 7:24 am

Could be the ammo, but I’ve had nothing but very good experiences with Freedom’s ammo. Haven’t bought any from them in at least 6 months though.

Only “test” I didn’t see above was whether or not you completely disassembled the bolt carrier group when you cleaned it. My immediate suspicion is that you’re over-gassed or have a weak mag spring.

Where’s the brass kicking out?
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