Dished primers?

[UrsaMajor]

Hi Guys,

This is my first post here on the Smith & Wesson Forum.
I have been a member for over a year, and have enjoyed the discussions.
I have owned an older Model 625 for a while,
a 1989 model with the firing pin on the hammer.
I recently acquired a brand new Performance Center Model 625,
with, as expected, a frame-mounted firing pin.
I noticed that the fired primers with the new 625 are "dished",
as shown in the attached photos. By "dished", I mean that
the entire face of the fired primer slopes inward to the firing
pin indentation.
I have seen this on two different brands of primers,
and the dished primers only happen with the new 625.
The first image shows a .45ACP fired from the older 625:

The next images shows a .45ACP fired from the new 625:

The next image shows a .45 Auto Rim fired from the older 625:

The next images shows a .45 Auto Rim fired from the new 625:

The load is 3.6gr of Clays behind a 200gr Lead RNFP.
The .45 ACP cases used Wolf large pistol primers,
and the .45 Auto Rim cases used Federal large pistol primers.
The primer strikes appear clean and the load is not very hot,
about 780fps.
Does anyone out there have any idea what could be causing the primers to "dish" this?

Thanks,

Jim

 

[AveragEd]

My guess is that the newer gun's firing pin is impacting the primers harder - almost but not quite hard enough to puncture the primers.

Ed

 

[cjw3]

Normal. Have a look at the firing pin bushing and you'll see why.

 

[Infidel_319]

Normal. Have a look at the firing pin bushing and you'll see why.

+1, my thoughts exactly.

 

[ImprovedModel56Fan]

Normal. Have a look at the firing pin bushing and you'll see why.

Thanks. I knew it was OK, but I never bothered to find out why. Now I know.

 

[Don_G]

Normal. Have a look at the firing pin bushing and you'll see why.

I've seen this on my 329, but I still have no idea why. I looked at the bushing and said "So.....?

 

[BLUEDOT37]

I've seen this on my 329, but I still have no idea why. I looked at the bushing and said "So.....?

My 686-6 leaves a dished primer indentation, my 686-0 doesn't. Looking at the firing pin bushings with a 10x loupe, the 686-0 bushing is flat across the face & the 686-6 bushing face is domed, having a small raised circular center than slopes evenly to the outer edge of the bushing. This, no doubt, is the "why"....but why only on some of the newer models? The bushing on my S&W 500 & 325NG are flat.

 

[AveragEd]

Not owning any centerfire S&Ws with frame-mounted firing pins, I was not able to understand cjw3's post. Thanks for the explanation.

Ed

 

[UrsaMajor]

Yup, you're right, the firing pin bushing is domed.
I hadn't noticed that.
It is flat on my 610.
And, of course, doesn't exist on the older 625.

Thanks,

Jim

 

[Don_G]

On my 329 the bushing is domed, but it looks like it is set below the surface. I had to use a straight edge to see that the center is just a few thousandths proud. Thanks.