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Posted: 12/27/2012 4:13:19 PM EDT
Hey y'all. Haven't been around here too long but have another question for your talented minds.

Working on my first AR build and have the lower completely assembled... only problem is the bolt catch lever is stiff as a board. The spring and detent were installed correctly but for some reason the catch is so stiff it will hold in in the "open" and "closed" positions and everywhere in between. Used some oil but to no avail. Any advice?
Link Posted: 12/27/2012 4:21:44 PM EDT
Originally Posted By oregonrunner4:
Hey y'all. Haven't been around here too long but have another question for your talented minds.

Working on my first AR build and have the lower completely assembled... only problem is the bolt catch lever is stiff as a board. The spring and detent were installed correctly but for some reason the catch is so stiff it will hold in in the "open" and "closed" positions and everywhere in between. Used some oil but to no avail. Any advice?


I know this sounds obvious but make sure you used the right spring and that it's not binding up in the channel. Also how loose did the catch fit in the slot in the receiver? What about the roll pin hole to bolt catch fit?
Link Posted: 12/27/2012 4:30:38 PM EDT
Well, made sure it was the right spring and detent. Before I put the roll pin in the catch moved with some generosity in the channel. Thinking on ordering a few more roll pins for another go around. Are poorly size roll pins this big of a problem? Everything else on this lower went together with relative ease...
Link Posted: 12/27/2012 4:33:31 PM EDT
I have a Bushmaster lower kit and the Bolt Catch had some burrs and was about .002 thicker than the DPMS kit Bolt Catch. On the Lower I made from scratch which I made to Mil-Spec dimmensions the Bushy would not ailow a .0025 shim before plating. If its a Bushy you may need to pull it out and deburr it a little.
Link Posted: 12/27/2012 4:41:57 PM EDT
It's a S&W MP15 lower with a PSA LPK. I kinda F'ed up (first build mind you) the end of this roll pin so I ordered two more DPMS as a possible solution.
Link Posted: 12/27/2012 9:07:13 PM EDT
[Last Edit: 12/28/2012 8:19:50 AM EDT by Direct-Drive]
I like to dry fit the bolt catch and operate it with the shank of the correct size drill bit.
I found an out of spec bolt catch (bore too tight) on the last build.
Installing it would have caused your symptom.
Link Posted: 12/28/2012 7:46:47 AM EDT
Is the hammer down?
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