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Curious about something

2735 Views 8 Replies 7 Participants Last post by  zargarex
Took it apart tonight to clean after a short range session yesterday.. I took out the striker(firing pin) assembly and noticed that the one side of the actual pin that protrudes through the breach face showed wear but not all the way around ? normal ? wear was on left .. I also noticed on the breach face that it appears that there is a milled indentation in the shape between a "V"&"U" which tapers toward the bottom of the breech face, deeper toward the firing pin hole, maybe a 1/16" long..

It does not appear to be "worn" in there it actually look like it was made that way.. is that normal ?.

Another question on the striker.. should the striker protrude through up to the flat face where the pin meets the barrel of the assembly, err... should the flat part where the pin forms reach the breech face on the back ?. does not appear that it does. just curious.

My pencil test on this thing is pathetic, hardly even moves the pencil.. yet i went through 100 rounds of WWB 115's no problem yesterday, although i had some surplus 9mm that it just would not ignite.. although i think it's more the ammo's fault then the pistol.

here's a picture..

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With a quick glance over your picture everthing looks fine. Some machining marks but nothing else.

The teardrop cut near the striker hole is normal and added on in later M&Ps.

Matt appreciate the reply, i'm still trying to figure out what it's for though ? it's not cut all the way through either, just on the breech face.. What purpose does it serve ?.

Anybody have a idea.. i would think if it was something to do with the striker it would have been cut all the way through the breech face ?.

Thanks again.

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The tear drop cut is to help reduce primer flow into the firingpin hole.

Appreciate the repsonse Dan..

My M&P .40 does not have the tear drop cut. Was this revision only on the .9 mm or did I end up with a surplus part on my MPF7XXX frame?

I'm not too concerned since my gun has been performing flawlessly.

I'm just curious also...
Mine does as well (rev N). The main reason I posted was to confirm that my firing pin had some uneven wear as well; in case someone else was searching through on it.
Dan Burwell said:
The tear drop cut is to help reduce primer flow into the firingpin hole.

Sorry to dig up an old post... but what is primer flow, and how does the teardrop help in reducing it?

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