Bolt and lower problem.

[cjd3]

So I've encountered this new problem. Bolt is locked back. If I hit the buttstock with a little force, the bolt will close, and if a loaded mag is in the magwell, it will chamber a round. Never happens on one lower, repeatable on the other with the same (only) upper. Any ideas?

[UWone77]

It's actually quite easy for the bolt to slam forward in the situation you described.

[VIPER 237]

That's normal. Your bolt catch spring may not be as strong as on your other lower, and/or it may not have as much contact with the bolt.

[WHSmithIV]

Pretty much all you could do is swap out the bolt release spring and bolt release catch. I have seen difference in bolt release catches from different lower parts kits that could be the cause of that being able to happen.

[cjd3]

Just did another check of both lowers, and they are more similar than I originally thought. Thanks for the insight and help.

[JHoward]

Yeah, if the BCG moves rearward the slightest amount, any rifle is going to do this.

[Dark1]

Most ARs do this I remember while I was deployed in Iraq some people would bump the butstock on the ground to close the bolt after clearing their M-4s

[Stone]

Yeah that 14" long buffer spring puts a lot of force on the BCG when its locked back. It doesn't take a whole lot of opposing force to drop the bolt catch. Perfectly normal...