Bolt catch won't release on first AR build

[JPS]

The bolt catch on my just-built AR will not release unless i pull back slightly on the charging handle.  I've taken it apart and checked, and it looks like it is assembled correctly.  Is this something that can be adjusted somehow?  Will it likely loosen up after firing the gun a few times, or should I get a replacement bolt catch?  Note that this is my first time building an AR/lower - newbie mistake is not out of the question.

 

Any ideas?

[mikegideon]

Pictures would help. With the upper removed and no magazine, the bolt catch should move freely, and the return spring should push the bolt catch down against the lower receiver.

[JPS]

I'll try to post pics tomorrow when I'm not working. 

When I remove the upper and magizine, it appears to work properly.  It only sticks when assembled and charged, and if I pull the charging handle back a little to relieve the pressure on the catch, it will release.

[Oh Shoot]

I'll try to post pics tomorrow when I'm not working. 

When I remove the upper and magizine, it appears to work properly.  It only sticks when assembled and charged, and if I pull the charging handle back a little to relieve the pressure on the catch, it will release.

 

I had one do that on an Omni polymer lower, just couldn't release bolt with the catch itself with loaded mag (Magpul or aluminum GI mags) short of tapping it with a hammer or something. Worked fine on empty mag, or releasing with charging handle with full mag. Figgered the actual dimensions of the lower itself were just a bit out of spec somewhere around the catch.

 

Know it wasn't the bolt catch parts because I took them out and used same ones in the TGO billet lower (sans roll pin), and used same unchanged upper, all good.

 

Probably not your situation, but thought I'd mention to cloud the issue. :)

 

- OS

Edited January 29, 2014 by Oh Shoot

[Dolomite_supafly]

So when you press on the bolt hold open with the bolt locked back the bolt hold open will not move?

[JPS]

So when you press on the bolt hold open with the bolt locked back the bolt hold open will not move?

That is correct. It will not budge until the pressure is let up by pulling back on the charging handle.

[JPS]

This is a TGO lower by the way, with an Anderson (I think) LPK.

[Oh Shoot]

This is a TGO lower by the way, with an Anderson (I think) LPK.

 

Well, then, something's out of whack with the three bolt lock parts or bcg/upper, can't imagine it's that lower.

 

- does it work if locked back with no mag inserted? if yes:

 

- does it work if locked back with empty mag, or just not work with loaded one?

 

and

 

- is problem consistent with different brand/type mags (ie, magpul vs metal ones)?

 

If you can narrow it down with those questions, I'd bet Dol or somebody will pinpoint solution.

 

- OS

Edited January 30, 2014 by Oh Shoot

[Dolomite_supafly]

So even if you hit it with the palm of your hand it will not budge?

 

I understand that it might be hard to push but I find it hard to belive a good solid hit won't release the bolt.

 

I would remove the bolt hold open. I would break the edges of the bolt hold open. I suspect when there is forward pressure at the top it is digging in at the bottom because of a sharp edge. If you break the edge it should fix it.

Edited January 30, 2014 by Dolomite_supafly

[JPS]

I had been trying with 2 different mags, 1 metal and 1 plastic, with the same results..  When I tried it this morning with a PMAG, it worked just fine.  I'm thinking it just won't work with my 'cheap' mags - does that make sense?  Those mags work fine in my other (Ruger SR556) AR.