S&W 629 Question

[mtgrs737]

A buddy picked up a like new S&W 629 with a 4 inch barrel at last weekend's gunshow for a decent price. This gun does not have a mark on it and locks up tight as a drum, it barely has a cylinder line. My question is: This gun has the frame mounted firing pin, the face of the breach where the firing pin is located has a slight convex surface. I have never noticed this before on a S&W as all that I have delt with before have had the hammer mounted firing pin. It appears that the area that is slightly convex is a bushing mounted in the breach face. This convex surface causes the fired primmers to be concave on the fired rounds, and I think that I saw some primmers that may of been perforated by the rather deep firing pin strike, there was black discharge on a few. There also seemed to be a slight hesitation when shooting double action maybe caused by the brass squeezing by the convex area. My question:

1. Is this normal for the newer S&W's?

2. Does anyone know what the correct firing pin protrusion measurement is?

[S.R.Custom]

(1) This is normal for early frame mounted firing pin guns. They seem to have gone back to the flat bushings on the latest specimens I've seen. It's one of those things where you ask, "what the hell were they thinking?" because it does cause hangups in the rotation of the cylinder, particularly with full power magnum loads.

Even if you ignore the hangup thing, it is very confusing. When fired, the case sets itself back against the frame of the gun like it always did, but because the bushing is convex, it flattens a primer more than usual, leading the shooter to think his loads are too hot.

(2) I have never seen a pierced primer caused by excessive firing pin protrusion. (Think about how a primer is made, and you'll understand why.) The usual suspects are hot loads, inferior primers, and weak firing pin springs, in that order.

FWIW, typical firing pin protrusion is .040", but can be as much as .050".

[mtgrs737]

Supermag,

So what to do about the slightly convex condtion? Will S&W fix it or can it be carefully filed, or peened down. Only a very small amount of metal would need to be removed. I agree with you, what were they thinking! Thanks for your reply, it is most helpful.

[S.R.Custom]

Use 320 grit on the end of a hardwood stick instead; it's hardened, and if you use a file you'll bugger up the frame before you get anywhere with the bushing. But even still, you're committed to taking out the firing pin because of the crap you'll get in the firing pin hole.

I recommend to just leave it. That's what I did. There's enough other goofiness going on in the S&W double action mechanism these days that you're not going to improve things much. (The MIM hammer and internal parts don't fit together in the same manner as before, so the action itself is simply rougher as a result.) You'll have to change how you read primers, though...

[44mag1]

Id call smith and wesson and talk to them, They have been very helpfull anytime Ive dealt with them