I am seeking striker advice

[Will Henry]

So, I have this old Wichita Mini action, which I recently re-acquired, out of a feeling of nostalgia as much as anything. Anyway, the old rifle shows some signs of abuse and I'm working on it. My question regards the firing mechanism. The original firing pin is set up so that protrusion can be adjusted by threading the pin in or out of the cocking piece, which bottoms out on the bolt sleeve when the rifle is fired (or dry fired). At the front of the firing pin is a flange against which the spring is compressed (just like on a Remington or Ruger or a host of others. There is a shoulder inside the bolt body which could act as a stop, if the firing pin is the correct length. In this case the firing pin would stop against this surface and not against the bolt sleeve. I am inclined to set it up this way; set the cocking piece to produce enough travel but clear the bolt sleeve and lock it in place. For the guys who are knowledgeable in this area, what would be your preference? Contact the shoulder in the bolt body, or contact the bolt sleeve?
I've seen some cratering of primers, so I plan to add a little weight to the striker by making the flange about .1" thicker on the new pin. I'll also change the shape of the pin tip a bit. WH

 

[msalm]

I would have it contact the internal shoulder in the bolt body. Also, when firing against a live round, will it even contact that surface?

 

[Will Henry]

It shouldn't. Ideally, when the striker is just right, the firing pin should penetrate about .030, I think. With .050 of protrusion, this should leave 15 to 29 thou of clearance when fired (depending on head clearance and primer seating depth). I might cut the protrusion back to .045. I'm leaning toward contact in the bolt body as well. Of course, the cocking piece has to come close to contacting the bolt sleeve or else I lose striker travel. I'm not sure why I found myself in such a quandary over this.
Another issue with this bolt is, because it is so short, there is not a lot of guidance for the firing pin. The tip of the pin, which stands up from the flanged striker, with no radius, is the only guiding portion. Although it has been in service for over forty years and at least four barrels, it looks fragile. I'm planning to bevel the hole at the shoulder so that I at least have a radiused transition to the pin tip. I'm making the flange larger as well, for a closer fit to the honed bore of the bolt body. I'll cut two notches in the flange to eliminate any air cushion effect. WH

 

[Alex Wheeler]

In actual use it will stop on the primer. So how it stops dry firing doesn't matter at all. Im not against adding weight but the 2 main things are fall and spring. Im no expert on that action but if you have issues with cratering weight is not the first place Id look unless its got an unusually light firing pin assembly.

Based on your second post I would be inclined to make a new firing and bush the boltface to guide the firing pin. You do no want to guide them off the flange of the firing pin. Rarely will the internal hole be in line with the firing pin hole of the bolt face.

 

[BoydAllen]

For those who not familiar, shell holder bolt face. Bolt has to be removed to load.

 

[Jerry Wick]

Here's a breakdown of the ignition system.

 

[Will Henry]

That's the reason a slight crater is a real problem; you can't get the fired case out of the bolt! I had to dry fire the thing to put the crater back in order to remove the case.
My action is from 1980. I won the Northwest Regional LV championship with it that year. I sold the rifle in 1982 and recently bought it back. It's a little beat up but I am determined to get it working at its former level again. The bolt handle had come loose at some point and been inexpertly repaired. Kind of homely, but it seems secure enough
I re-shaped the firing pin tip and adjusted the protrusion (050"). I set it up to hit on the bolt sleeve while clearing the inner surface by .010. I increased the striker travel by about .050 since there was room to do so.
I'll gauge the concentricity of the firing pin hole with the bore before I make the replacement pin. The reason I was thinking of guiding the pin with the flange is because there is so little length to work with and the tip is so spindly. Thanks, WH