Safety lever problem

Assembled a lower and the safety won't engage.

Rifle is cocked.

Removed the handgrip and safety lever. Inserted detent pin, depth gauge measured approx .173", same as others.

Removed detent pin, installed safety. Can engage in safe position, swings 180*.

Taking the safety lever and detent pin out, the detent pin goes into the safety lever to a depth where the full diameter of the pin is in the detent by several thousands. Does this sound right? Doesn't look that much different than the other guns but they work properly.

Are you sure that you are using the correct pin??. The safety detent is not the same as the pin for the forward pivot or take down pin. The pin is flat based, has a grooved shoulder at the backend, and is only pointed at the tip. Sort of looks like a small bullet.

Yes, it's the right pin. That's why I mentioned the depth gauge reading is the same as on other rifles with a properly working safety.

I've never had an issue with the selector not turning but have had it turn roughly. In that case, I either de-burred the selector detent channel or after making sure there wasn't anything foreign in the pistol grip's detent spring hole, shortened the selector detent spring, a coil or two, until the selector rotated smoothly. I take it you only have the one selector?