I own two S&W AR15-22's, and the firing pins keep breaking on them. I have broken six firing pins so far in 2 years
-I never dry fire,
-I don't oil the firing pin assembly
-CCI, Federal, Browning & Remington ammo.
-No Mini-mags
-The firing pins always break at the same place.
I shoot about...
You had asked how strong the polymer is. I have an AR15-22 that i have put over 30,000 rounds through, between both practice and competition. The only two parts that have broken are the extractor and the firing pin.
They are extremely tough.