I have an M&P10 (.308 Win) with which I have practiced quite a bit but with which I hunted for the first time last Saturday. Where I hunt for white tail deer we have quite a few feral hogs and I have regarded my M&P10 as the perfect weapon for taking out several hogs in any given sounder I might encounter.
Saturday morning I took my M&P10 to the blind and to my good fortune a big hog stepped out at 80 yards to cross the 40-yard-wide field before me. As he walked, I slipped the rifle out the window and began taking aim. Just as I got the crosshairs close to the hog I slipped the safety selector to "fire" and heard a "ping" I had never noticed in all my range practice. The pig heard the ping, l located me and ran on across the field. Expecting the sounder to behind him (back across the field), I trained the scope on the spot where he disappeared and, sure enough, out he came at a full run back across the field. I never caught up with him in his 40 yard dash and my desperation shot was behind him as he entered the woods at his point of origin.
Field tests are critical and I learned a very good lesson. But now, the question for you experts.
IS THERE ANYTHING I CAN DO TO ELIMINATE THE "PING" IN MY SAFETY SELECTOR"?

Mine has never pinged. Click sure but not ping. I have no idea what would cause that.

Thanks for your reply. I can prevent the "ping" if I press the safety selector in onto the frame as I turn it and allow it to move only very slowly into the final "fire" position, but this is difficult to do with gloves on because the glove material gets pinched between the selector and the frame and I don't always have time to focus so carefully on movement of the safety selector. The feel of that motion, however, is that a spring-assisted device pulling the safety into its final "fire" position with authority.
I did occur to me that as bad as the "ping" is for hunting, it would be even worse in combat.
Again, thanks for the reply.

Are you confident enough to work on your firearm? If so, yo could pull out the spring and detent to see if the nose of the detent is deforemed or it was installed backward.

If I remember correctly (it's been a while since I've had to do any work on mine), the detent and spring is held in by the back plate between the upper receiver and the castle nut for the buffer tube. It isn't setup the same as an AR15 where the grip holds it in place.

You could try removing the grip first to make sure but I'm pretty sure it runs through the back of the upper receiver than through the bottom.

The end of the detent facing the safety selector should be dome shaped.

Thanks for the path forward, but honesty requires admitting that I am not that confident breaking down such a valuable gun. I am trying to be disciplined about proper and timely maintenance of all my guns and learning how gun components work together, but I am not ready to start taking the M&P10 apart. I do have a very good gunsmith available to me, so I will practice more with the M&P10 now that deer season is over and get the best possible understanding of the noise and then take the gun to him with your insight. Thanks again. When I get it figured out and fixed, I will post the results here.

Maybe just squirt a drop of lube in there and work the switch a few times. It could just be dry and making the noise as the detent pops into place in the selector switch. Always try the easy way first...

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SIC SEMPER TYRANNIS

Makes sense. I will try it and report back.

I applied a small drop of oil to both sides of the safety selector both inside and outside the frame. No change. Working the oil in, however, made me decide that the sound is more of a pronounced "click" than a "ping". I think hearing it inside a deer blind with sheet metal sides when all else was silent caused me to think of it as a pinging noise.
As I work the selector back and forth, the "click" is clear and not a quiet or soft sound. If I pinch the selector between my thumb and index finger and move it back and forth slowly and under careful control, I can reduce the volume of the click and sometimes eliminate it. Otherwise, it seems as though this selector is simply made to pop firmly into its position on both the "fire" and "safe" end of its motion and when it pops, it makes that click noise.
I am surprised because all my other hunting rifles have a completely silent safety selector. Nevertheless, it may be that the M&P10 is intended to make this click and the only thing I can do is move the selector very carefully when game is within earshot.
Any other ideas?

Well it's going to make a little noise because the spring is pushing on the detent that 'pops' into place on the selector switch as it moves from safe to fire (and from fire to safe). You need to get some lube on the 'stem' of the switch where the detent rides on. It won't work it's way in there by just putting a drop or 2 on the sides. I don't think you will be able to totally eliminate the 'click because that's just the way it works. But, it will quiet a little bit with lube on it. All of the selector switches on my AR's, and every other one that I've operated have an audible 'click' when moved from safe to fire positions (and back again). It's just the nature of the beast.

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SIC SEMPER TYRANNIS

Once i got situated in the blind I would probably just leave the safety off.

Good luck with those hogs!

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Possum—The other white meat!

Thanks guys; I will make sure the stem is lubricated. I really appreciate the comment about the "nature of the gun". I have come to suspect that and appreciate the confirmation.
And I will take a different approach with this gun and hogs than I do with my other rifles and whitetail deer. The hogs are always moving, seldom feeding. Even without the "click", my opportunity with the hog in question was requiring a very quick maneuver to get a shot. When I hunt with the M&P10 in the future (especially when hoping for hogs), I plan to have the rifle in hand or across my knees with a hand on the grip, rather than standing in the corner of the blind. In that position, I believe the gun will be safe with the safety off. I will also practice moving the selector in "pressure positive" fashion, which will reduce and sometime eliminate the click.

Remember, you have a long coil spring in a tube next to your head, could be the source. I sure hear a ping with every trigger pull. Joe

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Wisdom chases me; I'm faster

That's the buffer spring. He's saying the safety selector switch is making a noise when manipulated. But, they all do that.

You can lube the inside of the buffer tube and the buffer spring and a lot of that 'twang' noise will go away....

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SIC SEMPER TYRANNIS