357max on sb1 interesting note (firing pin length)

[Whiterabbitttttt]

So, I'm close to perfect performance with my 357 max. Two things:

#1 I switched to a really heavy bullet (250 grains, and it shoots AWESOME!)

#2 Using SRP and getting lucky on a sweetspot for loading, I got accuracy AND the "primer flow" thing is nearly gone. I'm nowhere near max and the next load up shows potential for great groups too, but why? I'm accurate and I can actually see the primer crater go down and down and down as the loads go up, then start to crater again at the top load. I assume if I go higher looking for max I'll only crater more for a diminishing gain in accuracy at best, and cost me more powder.

Anyways, that means I'm 95% there! I did ntice something though. The firing pin sticks out a mile and a half. I first assumed it was an SB1 thing cause the pin is so huge, but thought I'd look it up on the internet. The internet tells me rifles should be .05-.06 on pin protrusion, and shotguns should be .55 to .65 on pin protrusion. My pin is well over .07" on firing ( cant remember exactly, but it is well over .07, and less than .08). Is this normal? If not normal, could this cause some primer flow/cratering/puncturing? And if it is not right, can I just pop the firing pin pin out, shim the pin, and reinstall?

(I have no idea how I would shim the pin)

Any thoughts as to whether the pin protrusion can be related to punctured primers or general primer flow?

[quickdtoo]

How are you checking pin protrusion? You should be using the hammer to push it forward while the transfer bar is up(trigger pulled all the way back while lowering the hammer), if you just push the pin forward, it won't be an accurate measurement since the hammer limits pin travel, not counting momentum. The most I've seen is about .065".

Tim

[Whiterabbitttttt]

It never ocurred to me that there may be more than one way to measure pin protrusion, and I gave it no second thought. I pulled the trigger and lowered the hammer on the firing pin. Held the trigger down and used a caliper to measure the protrusion with no barrel in place. I ensure the caliper is straight, understanding that if the caliper is at an angle, I will not achieve an accurate measurement.
 
I'll measure again and report back to the thread.
 
Thanks Tim!

[quickdtoo]

I use the tail of the caliper right beside the pin tip like you were measuring the depth of a hole, perpendicular to the standing breech as in  straight down the bore, without the barrel mounted of course. 

Tim

[Whiterabbitttttt]

OK remeasured as per above, just like before. .075. Do I grind the pin or is there another option?

[quickdtoo]

That or add a shim to the face of the hammer or frame. Has the frame or hammer been modified? Replacing the hammer would work if the hammer has been worked on.

Tim

[Whiterabbitttttt]

Not sure if the factory did anything when adding barrels. The frame was bought new and sent to the factory for new barrels untouched and unfired. Otherwise nothing.

Making a frame shim sounds challenging. How would you go about attaching a shim so it is reliable?
 
I could also stone the hammer at the contact point between the hammer and transfer bar. Would that be reasonable as well?

[quickdtoo]

That would work too, I've had to do that on a couple older hammers. But if it's just slight cratering, I'd leave it as is, I've had slight cratering on several centerfire chamberings with factory ammo, my first 243 Ultra Varmint did it consistently, but it's never been a problem.


Tim

[Whiterabbitttttt]

Now that sounds like wise advice. I'll put another 20 rounds of this "magic" load that had minimal cratering in it to verify consistent low cratering. You might be right there.
 

[Whiterabbitttttt]

I reduced the firing pin length. Caused problems.
 
The huntsman no longer ignites reliably (the primer, not the powder. if the primer goes, the powder goes). The 357 that I thought might not crater much anymore punctured every single primer. Shotgun seemed OK.
 
Definitely going back to the drawing board. Bringing the pin back out and starting over with a new bullet for the 357. When the huntsman primers ignite every time, no more frame work.