M2 firing pin length?

Had a couple of failure to fires on opening day with the benelli,ammo was mix of leftover falcon steel from last couple of years,didn’t get a chance to look at the shells as I ejected them quick smart to make the shots and they ended up in the lake so can’t confirm the primer was hit or not,have measured the firing pin and it is bang on 3.885in long,have had the gun about 12yrs now and I got it second hand so not sure how many rounds have been thru it.can someone measure their firing pin as a comparison please? Thanks team..