Finished my first lower with a few problems

[urikagold]

Finished installing my stag lpk into my Seekins lower and was a little disappointed. I can't get the safety selector to click into safe or fire. Under some inspection I found it doesn't look anything like the one in my LMT. The groove in between the detent holes is very thin and doesn't let the detent drop into place. It also feels like the detent is too big in diameter to slide in the groove. Everything else went good until I tried to mate the lower to my LMT MRP upper. To my dismay it wouldn't fit. I adjusted the set screw in the lower, but it did no good. The upper doesn't drop in far enough for the take down pin to align. I can dirve it in with a hammer and then they fit extremely tight. I don't think this is something I want to do is it?

[ColonelColt]

Will the hammer actually lock back fully? Does the safety rotate freely without the detent in place and the hammer cocked? It's entirely possible you somehow got a M16 fire selector for either an auto or burst gun, though this seems unlikely. And I think most upper receivers are tight at first. We got a brand new S&W M&P15T with the rails in at work the other day and the upper was extremely tight to the lower. The rear trunnion on the upper receiver was basically a tiny bit too tall which would have been solved in ten seconds with a fine file but being a new gun, we couldn't exactly do that.

[Eric]

Does your selector look similar to this Stag part, or different?
http://img.photobucket.com/albums/v503/AR15forme/IMG_8359.jpg

[urikagold]

That's it. I talked to John at Rainier today and got all the issues resolved. I ordered another selector, detent and spring and am going to try to do some filing on the one I have now. Maybe I can fix it myself. As for the upper to lower fit I guess it is just going to be tight. This is my first lower build and I didn't know what to expect. Everyone on here makes it sound so easy. I was surprised to run into a couple of issues.

[federalist22]

I too had issues with my Seekins lower and the safety fitting weird, as did a friend of mine. I replaced one (standard RRA LPK safety) with a RRA Star Selector and it seeks to be "ok" after the swap and a slight file of the detent tip, but not feeling like what the safety movement in my RRA and S&W rifles is. My trigger is a Timney and my upper is a Sun Devil.

[urikagold]

What upper did you put on it? I have an LMT MRP that fits super tight. My MRP CQB upper fits just as tight. My buddies RRA upper fits super smooth. I would like to put another upper on it someday, but it is kind of hard to test fit an upper when you have to order them online. Not too many gun shops around here stock them.