So I installed my first lower parts kit last night and it went pretty smoothly overall.  Got the front pivot pin in place with no issues, no scratches on the receiver from installing the bolt catch, and only lost the detent spring for the rear take down pin.  That sucker shot out so fast I didn't even notice it when it happened, but it is gone forever.  I already ordered some replacement springs and detents to have on hand.  

The problem I am having, however, is that the safety selector is extremely loose and will not stay in the position selected.  The detent is in place and installed correctly, and the spring was in place as well.  I tried two different grips (the one included in the Daniel Defense LPK and the Ergo Sure Grip I will be using) and had the same problem.  Is this likely a problem with the safety selector itself?  From my research the Daniel Defense LPK is supposed to be one of the better examples so I'm not sure what the problem could be.  Any help/guidance is appreciated.

EDIT: Just wanted to add that I already spoke with Primary Arms and they are sending out a replacement selector, spring and detent they had available to try out and hopefully this will resolve the issue.  Just looking for opinions on whether or not this is likely to be the culprit since this is my first build.

The right side of the selector has a channel machined into it where the detent pin rides.   On each end of the channel there is a divot where the detent pins clicks into when the selector is rotated completely to fire or safe.   You can look at the channel and divots to see if it is machined correctly.  The divots should match the size of the end of the detent pin and the channel should be sharp, straight and smooth.   The divots should be at 6 and 9 o'clock.

The selector detent hole in the lower receiver should be exactly at 6 o'clock and aligned with the centerline of the selector hole.

You can also press on the selector detent pin with pin punch or allen wrench, etc. to apply pressure to the selector and feel if it rotates smoothly and engages the divots correctly.

what brand lower did you install the lpk  in?

With the selector out of the lower: Insert the detent into the lower w/ the spring & grip. Does the detent stick up out of the hole?

Sounds to me like the selector was installed the wrong g direction.

Wrong spring in safety selector?

I don't have an extra to compare it to as of yet but will do that when the replacement arrives.  I did notice the channel and the divots on either end.  The selector worked when installed but it did not click into place like on my LMT lower.  The selector detent hole is at the 6 o'clock position on the receiver and when the detent is dropped in place and the receiver held upside down, it sticks through the hole (didn't pay attention to how far through, though).  I'll try re-installing it and pushing with a punch to see if that changes anything.  



It is a forged Spike's Tactical lower that I got brand new.



The detent did stick up out of the hole when the lower was held upside down.  I will install the grip and spring in addition to the detent and see if it pushes it any further.  How far into the selector hole should the detent stick up?



I'm getting sent a new spring as well and will compare them side by side to see if the one in the Daniel Defense kit was too short.  But it was the only spring left in the kit and was definitely the selector spring.  


Thanks for the responses so far.  It is appreciated.

Clean the hole out.

What do you mean?  There was nothing in any of the holes on the receiver which would be blocking anything.  Everything went it where it should have, but the safety selector was not snapping into and out of position.

How about the little hole in the grip that the spring slides into?   Does it line up perfectly to the selector detent hole in the receiver so that there is no binding of the selector spring when installing the grip?

Put it all together like I said & take a pic.

The detent hole could be a tad undersized or the shelf could be too high not letting the detent stick out far enough.

Here are pictures with the safety detent installed with the spring and grip, but with the safety selector out.  Is that the depth it is supposed to stick up?  Anyone happen to have a photo of theirs installed with the selector out?

Received the replacement part from Primary Arms:

Daniel Defense selector on the left; DS Arms replacement selector on the right.



Daniel Defense selector on the left; DS Arms replacement selector on the right.


Installed it and it's tight but works fine.  The springs and detents are exactly the same length between the two kits, but the reason why it was not working was due to how deep the cut was in the Daniel Defense selector.  It was too deep for the detent to do its job.