Help with 357 mag firing pin / primer issue

[Blanco]

Any ideas or suggestions would be appreciated.
The weapon is a single action Cowboy style .357 Magnum revolver. This gun is new to me so i cant answer to any previous issues.
This model in particular is only marked Germany .357 Magnum. Evidently there were a number of these imported in the late 60's and early 70's ?
The gun appears quite well made and is tight in all the right places. Shooting it reveals it to be quite accurate.
The problem has appeared after about 100 rounds in it since I have had it. The problem is that the primers are cratering and bulging enough to lock up the cylinder.
I am shooting my hand loads which I consider fairly pedestrian. Win sp Mag primers with 9 gr. of HS6 and 125 Gr Lee RF PC cast boolit. QL shows this to be 1160 FPS...
At first I thought there was a action problem, but after a teardown and inspection there were no apparent issues found with the pistol.
I tried several empty primed cases and found the problem remains with the blanks. The primers are ignited without issue but the cratering still appears.
my guess is a damaged or mis-shapen firing pin. This gun has a round piece that houses the pin and spring in the frame. The pin is aprox 1/8" at the tip with slightly radiused edge and flat face. My thinking is the pin might need to be slightly pointed?
I will put some pictures up in a few min.
(almost identical to this ..HWS Bounty Hunter .357 Magnum EAA Import mfg H. Weirauch Suhl )
the current version appears to have a transfer bar added that mine does not have.

After removing the grips i found it is a Herbert Schmidt Model 121

[Blanco]

183858183859183860183862

[seppos]

You should not point it as the possible cause is that part of that primer blows to the pin hole.

I asume that the problem is that the firing pin somehow bounces back exposing the pinhole. It should block it during high pressure phase. Harder primers or stiffer hammer spring might help. Somebody might have tried to lighten the trigger by substitung the original with a lighter one or cutting the original a bit shorter.

S

[Blanco]

It appears to only deform the primer by raising the corner a fraction. It does not pierce the primer.
The primer is not raised in the pocket but rather the primer face is deformed.

[merlin101]

Is the firing pin hole worn a little oversize? Ifso that will allow the primer to 'flow' back into the hole and will lock up a tight action.

[Blanco]

There is no observable slop or oversize firing pin hole. There is no front to back or up and down slop in the cylinder it is nice and snug.
the face of the primer is almost slightly domed

[pietro]

.

Have you shot any commercial ammunition through it, to eliminate your handloads as the cause ?

If not, I respectfully suggest that you do so.


.

[varmintpopper]

Check the end play of the cylinder, too much end play may be your problem.

Good Shooting

Lindy

[44man]

Pressure drives the pin back, also the hammer. It leaves an open hole for the primer to expand into.
Might be a poor designed firing pin that leaves a gap. Or a too light hammer spring.
The distance a primer can push the hammer back is amazing. I had a picture of it near full cock on a SA. I suspect the hole for the pin is too large or the pin goes back too far leaving an open hole.
Pressure at the primer is high and it will flow.

[runfiverun]

the firing pin is driving the edge of the primer against the side of the case causing the ridge.
you just need the bushing replaced so the firing pin hits closer to the center of the primer.

[243winxb]

the primer is almost slightly domed Increase powder charge by a grain or two.

HS-6 From 8.5 grains to 11.6 grains

[Blanco]

the firing pin is driving the edge of the primer against the side of the case causing the ridge.
you just need the bushing replaced so the firing pin hits closer to the center of the primer.

This is my guess ... I found that Bobs gun parts appears to have stock on the bushing, pin and spring

[243winxb]

I am shooting my hand loads which I consider fairly pedestrian. Win sp Mag primers with 9 gr. of HS6 and 125 Gr Lee RF PC cast boolit. QL shows this to be 1160 FPS... The PC lowers friction, makes the load even more Low pressure. ​ [smilie=b:

[skeettx]

Interesting, of course you will get set back on a primed only case
But set back with loaded ammo is either too mild or too hot.
Or eroded hole or weak spring
Looking forward to your research
Mike

p.s.
Looks like you gun was proofed in December of 1962 that is 1262

http://www.shotguns.se/html/west_germany.html

[lylejb]

Looks like the primer is setting back, but not the case. This indicates a too mild load. As an test, try a few loads with a faster powder like bullseye or red dot. Also try a few near max loads with 2400 or w296. I'll bet your primers stay flat.

[swheeler]

This ^^^^^^^