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Old January 16, 2011, 12:40 PM   #1
MSD Mike
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Join Date: October 16, 2009
Posts: 164
Model 19 Primer problem

This might belong in the reloading forum but i believe its a gun problem so I will start here.
I have a Smith Model 19 that when shot with .357 jacketed rounds the primers will crater and sometimes pierce. The same loads in my other 19, 66 or Ruger Blackhawks are fine. The current load I am using is 8.1 grains of Unique with a 158 GR. XTP, Winchester brass and Winchester standard small pistol primers. Velocity varies a little depending on the gun but both of my 4" 19's run around 1150 FPS with this load. For the record, this gun has simaler problems wiht factory loaded 158 Gr. JHP .357 ammo. The gun functions perfectly with all 38Special ammo and lower pressure cast .357 loads.

Any input would be appreciated,

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Old January 16, 2011, 01:37 PM   #2
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Without actually seeing the gun I would suspect worn/eroded firing pin bushing or excessive cylinder endshake
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Old January 17, 2011, 12:11 PM   #3
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+1 hard to tell without seeing. Are you 100% sure there is no carbon rings that have polished to shiney in the cylinder holes? I've seen cylinders with carbon rings that haven't been aggressivley cleaned as well as they should be- due to snakes or plastic brushes- that leave the carbon rings shiney and difficult to see. This could be holding your .357 rounds closer to the shroud where .38's will take their normal seating.

Edit: And, a roll crimp on the cast bullets would have a slightly shorter OAL than a taper crimp, right(?). Just a thought.
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Old January 17, 2011, 02:13 PM   #4
James K
Join Date: March 17, 1999
Posts: 24,129
Have you had the hammer spring (mainspring) lightened or the hammer bobbed?

Contrary to most notions, pierced primers are NOT the result of a sharp firing pin, excessive firing pin protrusion or high pressure. They happen when a weak mainspring or light firing pin/hammer allows the primer's internal pressure to force the firing pin back and extrude some of the primer metal into the firing pin hole. A light firing pin or hammer, or a weak firing pin or hammer spring may be enough to fire the primer but not to support it against the internal pressure.

That is when you get excessively cratered and pierced primers.

Jim K
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Old January 17, 2011, 05:33 PM   #5
MSD Mike
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Join Date: October 16, 2009
Posts: 164
Thanks for the input guys, this is a nice gun but has a bunch of rounds through it. I will check for to much end shake and a shake worn firing pin bushing. Jim, I had not thought about the main spring being weak but what you say makes sense. The revolver is unmodified but the spring might be worn do to use. The action feels great and I don't think it is overly light but I have a new stock spring I can try. The firing pin shape looks ok but it does seem to protrude a bit further than my other K-Frames. I will measure and see if it's out of spec.

10-96, I do shoot a lot of 38 Special but clean the gun afterwards. There doesn't appear to be any carbon rings and my 357 loads (cast or jacketed loads) always drop right in and click right down on the rim of the cartridge.

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