1stTimeBldr

The Elftmann Tactical Ambi AR Push Button Safety is installed and functioning properly. It provides enough clearance for the trigger pull. Thanks to the commenters.

While it may be possible to do that without compromising safety, I do not plan to make any mods to parts. Easier and safer to replace the lower.

A $35 fix is a much cheaper alternative than a new lower. I think I will give that a try. Thanks!

My replacement safety selector arrived, and while the overall dimensions were identical, I saw that the well for the detent was cut much narrower. I installed the selector, detent, pistol grip, etc. - and as the safety detent engaged I felt the selector pop out a bit towards the lever side. Exact same problem. The clearance between that and the trigger bar (not sure of the terminology) is so small that this prevents the trigger from firing. So, it is either a defect in placement of the detent hole (factory drilled) or in my milling of the fire control group pocket. Although it seems unlikely, I am tending towards the detent hole being misplaced, because on every other AR, the selector switch is flush with the lower - not pushed out about a millimeter (see attached picture). Either way, I think this lower is a dead issue and I need to start over.

No; the safety gets installed at the same time as the grip and detent. When the detent engages the safety, it pushes the safety about a millimeter inwards, and that blocks the trigger from acting.

This is probably the issue. The hole was pre drilled, nothing I can do about that. I am hoping that the on-order safety is just a little narrower, enabling the trigger to clear the safety. If not I think I am out of luck.

The selector is a no-name that came with a lower parts kit. Interestingly, the replacement I ordered is a Battle Arms. They all have that same lip or rim to fit the hole drilled in the lower. The problem here seems to be that the detent is pushing it into the well a bit. I should get the new selector in a few days and hopefully that fixes it.

I believe I have found the cause. When I install the safety selector (before the detents, spring, and grip) and push it all the way through so that the selector lever is flush with the surface of the lower, if functions normally. During grip installation, I can feel the detent engage and the selector pushes out to about a millimeter above the surface of the lower. The selector crossbar has a raised lip where it goes into the hole on the other side of the lower - and when that pokes out into the well, that's enough to prevent "Fire" from functioning. So, I know the cause but not the fix. Is this just a bad selector?

Photo below. The pistol grip is attached.

I am in the final stages of building a JMT 80% AR-10 polymer lower. Milling went ok, and basic parts installation (pivot pin, mag release, bolt stop, trigger) all went ok. When I install the safety selector by itself, everything works normally - drop-in trigger releases on Fire, does not release on Safe. When I install the detents / springs and pistol grip, the trigger no longer releases on Fire. With the grip installed, I can move the safety selector between Safe and Fire easily and I feel the detent engage in both positions. I have tried the following troubleshooting steps: Install safety selector only: Trigger functions normally Install safety selector, and grip screw only (no grip or detents ): Trigger functions normally. Install safety selector, grip, and screw – with the screw backed out several turns (there is about a millimeter of space between the grip edge and the border of the grip mount on the lower. I did this because several posts mentioned that the screw might be overly tight.): Trigger does not function Install safety selector, grip, and screw fully tightened: Trigger does not function Take it all apart – Trigger functions normally I am at a loss – I do not know how the grip could be affecting the trigger. Any ideas?