Earl, I believe that S&W uses a firing pin spring in order to prevent a "slam fire" when the bolt slams into battery.. I don't believe DPMS uses a firing pin spring in their 308 AR, and I'm not sure about ArmaLite's AR-10... that spring is there as overkill, all 308 AR pattern rifles will leave a slight dimple on the primer as the bolt is released, whether using the slingshot method or the bolt release. Doesn't hurt anything, and has never been a problem in a well maintained fire arm with compatible parts...

I would remind all, that Smith and Wesson produces the M&P 10,, it is not a DPMS pattern rifle, nor is it an AR-10 which is proprietary to ArmaLite, so it is technically not an LR308 which would be Rock River, but generically would be referred to as a 308 AR..

Does your firing pin have visible damage?? or is your weapon suffering from reliability issues?? I would return it to S&W in either case, in order not to void the warranty...

hope this helps, Billy

I would add that while you might request a firing pin from S&W,, I rather doubt they will send you one, but it won't hurt to ask,,, I would add that prior to contacting S&W, I would return the rifle to factory configuration in order not to void your warranty.. they are very particular about AR's in general, and the M&P 10 in particular.

feel free to PM me if you prefer not to answer these questions on the forum... in my experience S&W has built a very fine rifle,, but there are some parts that are proprietary,, they really prefer we don't go messing with their rifle honestly..

the main reason I bought a WC-10,, LOL