AR issue.

[BigMike]

I recently got a PSA complete upper and their lower parts kit, installed in all on an Anderson lower. Took it to the range today and it's having a wierd malfunction. On the last round, the bolt carrier is being caught by the bolt catch, instead of the bolt face being caught. The bolt face is about a half inch ahead of the bolt catch and it's setting on top of the magazine far enough forward not to catch the first round on the next magazine. It cycles perfectly.
I'm using a mil spec metal magazine as its the only one I had with me. Going to try a pmag in the morning. I'm shooting federal 55 grain .223 ammo.
Is it new gun break in jitters, mag catching, gas problem, to weak ammo, or...?

 

[Necrosis]

Pictures would help. Is the bolt catch assembled correctly?

 

[JDG.]

Is it a pistol? How is the ejection pattern? Sounds like your saying the carrier is catching the bolt catch, not the bolt?

 

[JDG.]

Some common causes of that issue are weak ammo or rifle spring in a carbine buffer including some combination of rifle/carbine buffer/spring mixups.

 

[BigMike]

It's a 16 inch upper. I think the bolt catch is assembled correctly, big end up little end down, spring in first then the plunger. Ejection I have no idea as I'm shooting inside against a wall. I used the buffer and spring as they came assembled from PSA.

 

[BigMike]

Is it a pistol? How is the ejection pattern? Sounds like your saying the carrier is catching the bolt catch, not the bolt?

Yes, this.

 

[BigMike]

It was my first lower build that took a hammered pin instead of threaded pin in then bolt catch, it fit pretty tight. Could it be tight to the point it the bolt runs past the bolt stop before it gets into the fully raised position, and catches on the carrier instead?

 

[Necrosis]

Does the issue still occur when you cycle the bolt by hand?

 

[BigMike]

It does not.

 

[jeep78]

Are you running it wet?

Sounds like break in on a new AR. Running the boltcarrier wet helps short stroking.