AR-15 Function Issue

[CLICCO]

So, I finally completed my first AR-15 build. Stag-15 lower, Stag lower parts kit, and Stag 2H upper (with bolt carrier group). I brought it to the range tonight to put my first rounds through it. I was using 3-USGI 30-round mags, which have freshly installed anti-tilt followers and new springs.

My first 30, or so, rounds fired without a hitch. Then during a course of fire, a round was chambered, I pulled the trigger, but the round did not go off. I waited...then ejected the round and saw that the primer had not been struck by the firing pin. I manually cycled the bolt to chamber the next round, pulled the trigger and it fired. The rifle seemed to function normally when during another course of fire, I pulled the trigger and the round in the chamber discharged and extracted, the next round was fed into the chamber, but the bolt did not fully close on the newly fed round. I proceeded to eject the magazine and remove the chambered round. At this point, I thought it might be a lubrication issue? So, I liberally applied gun oil to the bolt and manually cycled the bolt several times (it felt somewhat sticky). After that, things seemed to be running well (despite the oil leaking out of various parts of the lower receiver).

Does anyone have any thoughts on what my function issue(s) might be and what I should do to address the issue(s)? Is this just an indication that I have to keep the bolt carrier group VERY lubricated for proper functioning?

 

[vellnueve]

Possible that the bolt didn't fully close on the failure to fire? Did you look?

As for the bolt not fully closing on the other round, that's what the forward assist is for. It happens.

Run 300 rounds through it. Don't drown it in lube, just give the internals a quick spray with CLP and shoot it, but you may just need a break-in period.

 

[TomH]

What ammo were you using? If you were using some weak stuff you could have cycling issues. Run some M193 through it! I'd guess it needs some wearing in as it's new. Keep an eye on the bolt and use the forward assist if you aren't pushing a round in all the way.

 

[Finalygotabeltfed]

Agree,

From past personal experience and witnessing others breaking in new ARs, they need to be run wet with oil and using good ammo for break in for a couple of hundred rounds to polish the mating surfaces in the bolt and receiver.

Remington, UMC or other weak ammo won't do well for break in.

Sellior&Bellot, M193, M855 or other known full power milsurp should be used.