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AR 15 issues

Jason m

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Built a AR over the last year and today was the day I took it out for the first time. Well it was working fine, I will say the used upper is a A2 and is a very well used upper. I dont know the history of the upper but it was very dirty and well used. But it did group very well at 50 yards.

Ok the issues I had, I would pull the trigger one round would fire then as I released the trigger the gun would fire another round, again this fired when I released the trigger. Not every time but at least 5-6 time out of 40 rounds of brass ammo.

Second issue and maybe related is out of the 40 round fired today 3 were miss fires. Seems the firing pin struck the primer but not hard enough. One out of 40 I would say maybe a bad round but 3, na.

Reading on AR 15.com it seems the disconnector could be intalled backwards or bad, but the parts kit was a Cmmg which I thought was a good one, the lower is new ( I forget who made it ). Again maybe the two problems are related but then again maybe not.
I did not build the lower I had a good friend do it and I watched, hes built several lowers so I'm thinking he is not to blame here.

Jason.
 

Fixxah

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Did you build the lower? Are springs in correctly? Tried the upper on another lower? Is the bolt all gunked up?

-tapatalk and Devin McCourty blow chunks-
 

PmedicJ

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Function check
1) Install upper. Ensure the chamber is clear.
2) Ensure the hammer is cocked. Turn off safety. Pull trigger. It should fall.
3) Re-cock the hammer using the charging handle. It should stay cocked.
4) Turn safety on. Pull trigger. Hammer should NOT fall.
5) Turn safety off. Pull trigger. Hammer should fall.
6) While holding trigger down, re-cock with the charging handle and let it slam forward on its own (don't ride it down). Hammer should NOT fall. If it does, you have a problem with the hammer/disconnector engagement.




My guess is that you're either bump firing (not likely) or the disconnector and hammer are not playing nice.
Weak disconnect spring or trigger group problem, any pins loose? Could be just an out of spec trigger group to begin with.
 

Canndo

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I'd suspect the disconnector or disconnect spring. Is the spring missing or upside down. The large coil should be at the bottom
 

Jason m

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No as I stated I did not build the lower, I had a friend who built several in the past do, I watched.

I will check the spring and see if its in backwards.

Jason.
 

Supermoto

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Sounds like there is a timing issue with the disconnect and the sear. The hammer is being released too soon by the disco and is not being captured by the sear. I would replace the entire trigger pack
 

Jason m

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Ok, looked over the gun a little better today and found this pin walking out, hope no dammage was done to the lower itself, does not look like it did but i'm a little nervise.

AR151.jpg


AR152.jpg



Jason.
 
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