I wanted to put an ambi safety on a couple ARs for my wife. She's a Southpaw shooter, so I looked for a safety that allowed the levers to be swapped from side to side.

I found an inexpensive one that looked real good. The short lever was "scalloped" and would interfere with normal grip even less than just a short lever. So I ordered three. Which turned out to be ideal because only one of the three worked right.

The first one I installed would not move from safe to fire, or from fire to safe when assembled in that position. All the strength in both my thumbs would not move it either way.

The second one (assembled in the safe position) moved quite normally from safe to fire, but there it stayed. Again all the force of both thumbs wouldn't budge it.

The third one, once installed, worked perfectly. Lines up at exactly 9 and 12 o'clock. No slop or wiggle. The levers don't drag on the lower. Perfect! And it feels great. I love the design. I'd replace some of the existing ambi safeties on my rifles with them.

By the way, all three were assembled with the same detent pin, spring, and grip.

I've installed a few ambi safeties before and never run into this. All were a straight Re and Re and worked correctly right out of the box.

I contacted the manufacturer asking to swap the non-functioning ones for a couple good ones. I was told that the safeties were fine it's just that some detent pins were "too sharp or pointy". All I had to do was file or sand down the point and the safeties would work fine.

My first take is that customer service is shining me on. All the drop in parts I've ever put into an AR did just that dropped in, worked fine, lasted a long time.

Has anybody else run into needing to re-profile a detent pin? The same detent pin was used with all three safeties. It seems to me that if the pin was the problem I'd get the same results with all three safeties, not one works, one works 50%, and the third doesn't work at all. Or the original safety would have had a problem.

I have several spare detent pins. Visually I can see no difference. Cutting a new profile on a detent pin is not an issue. I don't have a suitable lathe, but I could just chuck the pin up in my Foredom Tool and spin it up against an abrasive.

I appreciate any help. Thanks.

Vic.

IN!  Because something is not right, or out of spec, and I'd like to hear what other people think.

Did you look at the selector itself?  Particularly at the point where the detent fits into the selector body.

That might be too deep which would create the issue you described.

Was the hammer cocked so the safety could move?

This has bit me before.


Make sure the body of the selector is facing the right way with the cut out for the detent pin in the correct orientation.  On my preferred ambi safeties flipping it around gives you the option of 60 or 90 degree throw, and then you put the levers on whichever side you want.  If yours is set up this way, be sure you are putting the levers on in the correct orientation for the body of the selector.

Yes, hammer was cocked.

Yes, hammer cocked. And these safeties can do the 90* or the 45* by flipping ends. I was using the 90* end as I'm not interested in the 45* safety position. Too much muscle memory for the standard positions built up over a lot of years.

Thanks for all the replies.

This was my first guess. Visually I don't see any indication that the detent pin seats too deep in the pocket in the safety (using a headband magnifier). I can clearly see the line where the cylindrical part of the detent pin ends and the conical point begins above the top of the pocket the pin fits into. I would think that as long as the straight side of the detent pin is not bearing on the safety, then it's just a case of the slope of the detent pin point sliding up the slope of the pin pocket in the safety. And yes I put a drop of lube in safety pockets and connection grove.

I can get a better look at it. I have a B&L low power stereo microscope (well, my wife does). I just need to get new bulbs for the illuminators. I'm not sure what that would tell me.

I think, if I really want to put the time into it, the thing to do is to jig up a dial indicator. Take a lower, install the safety that works 50%, invert the lower in my vise, drop in a detent pin and a piece of flat ground drill stock the same diameter as the pin and just long enough to slightly protrude above the bottom of the lower. Then using the the bottom edge of the lower as my base/zero point, put the dial indicator on the protruding drill stock. I would think this setup would allow me to get measurements on; full pin seating depth, maximum rise to move into the connecting groove (does it have a "speed bump" to ride up over?) and height in the groove.

I could also do the same measurements on the safety that doesn't work at all and on the original known good safety and some other new ones. I just received an ambi from Aim Surplus and I think I have ambi safeties from PSA and one in packaging I don't recognize, plus several standard safeties taken from working rifles.

I just wish these worked. I REALLY like that scalloped short lever.

Some detents are as sharp as an awl. The KNS Precision detents that I've used had a slightly different tip profile than most, with a blunter tip. Might work for you. They're stainless, hardened and nitrided. Unless you're grouping with a larger parts order, shipping probably costs more than the parts.

Another possibility - either the safety selector spring may be too stiff or the hole in the grip isn't deep enough.

The ejector and safety selector springs are identical.

Try using a take down or pivot pin detent spring.  They're weaker and I'm pretty sure they'll fit.

Can't hurt to try.

Just for shits and giggles remove the selector and grip and drop the detent into the channel.  How far does it protrude into the lower?