I learned something about the adjustable firing pin.

I learned that my newer 10T-ST has an adjustable firing pin, and I accidentally changed it from the factory setting. I made the firing pin extend it’s maximum length into the primer. I learned this was a bad idea when I took my first shot with the adjustment.
I pulled the trigger, the gun fired, and the firing pin extended so far that it made the case pop out of the bolt face. The case was stuck in the barrel and the extractor came apart.
After I found the small bearing and spring, and figured out why it all happened, I put the extractor back together, adjusted down the firing pin, and got back to normal shooting.
Now I know that it’s not a great idea to tighten the firing pin spring a lot and then adjust out the firing pin.


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Most factory firing pins are already extending too long to be at their maximum effectiveness. Do some searches and learn about the best length....

The firing pin thing we can fix. The over pressure you describe needs to be discussed. Was it a reload? Or name of the ammo manufacturer and other details would be good.

How did you measure your protrusion and what did you end up with. I prefer a depth mic but a skilled machinist or someone who is knowledgeable of dial caliper usage can make it work. I hope you were not eyeballing it. The fact that you considered making it longer is concerning.

You only need the FP set at .035” protrusion.

Case doesn't extract so well when the extractor is in pieces...LOL . Been there, done that, but not the same way.

If your bolt is similar to my model 12's, (does not have a cocked indicator) there are two dimensions you need to be concerned with. First is firing pin protrusion, generally set to .045 to .060 at the factory, probably to account for slightly different cartridge lengths in factory ammo. .035 is minimal and is fine if your handloaded ammo is carefully sized. Some factory ammo may not fire at that dimension. I've encountered this before.

Secondly, with the cocking pin at the bottom of the cocking ramp, there needs to be some clearance between the cocking pin and the bolt body cutout. You don't want it slamming into the bolt body before the firing pin hits bottom. I find it easier to set this up with the firing pin spring removed, measure the firing pin OAL with calipers and then reassemble with the spring while CAREFULLY centering the flat in the lock washer so that it doesn't bind on the pin during travel.

This would be a good time to add a bolt lift kit too. Take a 38 cal brass and cut the body down to the web. Find a steel ball about .185 dia and place it in the primer cup. Place that in the cocking sleeve, add a bit of grease, and assemble the Bolt Assembly Screw one and a half turns. Cock the firing pin, and finish tightening the BAS.

I made the firing pin longer because I had factory ammo that was not firing. I could see from the dimples in the primers that the firing pin was not extending far enough. The ammo was factory Winchester Super X I was using to get close to zero before I used my better ammo. But even after I sorted out the firing pin problem I could not get consistent groups with the winchester ammo. So, I set up my chrono and found out that I had a 324 fps spread in the ammo. No joke. I shot all 20 rounds and the fps ranged from 2490 - 2814. It wouldn't surprise me if my first shot with the long firing pin was also a hotter load. But after I adjusted the firing pin I had no other problems.
I didn't have a micrometer with me at the range, so I pulled the firing pin in further than I knew it needed, and slowly adjusted it out until the rounds would fire.
What I learned from this is the adjustable firing pins have two factors and they both need to be correct; the spring tension and the firing pin protrusion.

In my opinion if you had to extend the firing pin protrusion to get it to fire, you had a serious headspace issue. Either the headspace setting was off or the ammo was manufactured short.