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Old 07-03-2020, 11:23 AM
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Reshaping the firing pin on my Montana Varminter



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The firing pin was reshaped at my desk and the "pinprint" looked good testing with empties. At the range with Eley Match with a rim thickness of 0.036 there were two FTF out of four.
Tried CenterX which has a thicker rim and had one FTF our of five.
The pinpoint on the FTF rounds appeared to be more inside the rim when eyeballed.
Removed the firing pin and using one hammer as a makeshift anvil, six taps with the other hammer produced consistent ignition with all ammo tested and the pinprint in relation to the rim was more consistent. FTF's were eliminated and at 100 yards with Remington Eley Match 1062 a ten shot group measured 0.74 CTC.

I was always taken with blacksmithing but never thought I had the knack . . .
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Old 07-03-2020, 12:08 PM
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Do you have any pics , Im cant picture a before and afte
How did you reshape the pin first off ? r
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Old 07-03-2020, 12:58 PM
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Filed off the top so the pin-print is inside the rim.
The theory being that crushing the brass rim detracts from the energy.
I did not collect any of the brass but a previous reshaping picture might still be available. Will look.



This may not be a Cooper pin-print but the left is an Anschutz 1416D unaltered and the right side perhaps a CZ455.

Last edited by horseman2; 07-03-2020 at 01:01 PM.
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  #4  
Old 07-06-2020, 09:45 PM
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I had the same problem with FTF after reshaping the firing pin tip on my TRP-3. Yes, you can take too much off the top of the firing pin and have the strike too far inside the rim. I had an extra pin that I profiled correctly to fix the problem.

Last edited by elohssa63; 07-06-2020 at 09:49 PM.
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Old 07-06-2020, 11:21 PM
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Now you can try to re-re-shape your FTF pin!
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Old 07-07-2020, 11:23 PM
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Bill Calfees book mentions reshaping firing pins.. I never understood the exact procedure so I didnt do it.
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Old 07-08-2020, 08:22 AM
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Re-shaping the firing pin is the very last thing you would do after trying everything else possible to improve accuracy, and you lay awake at night trying to think of something else to do. The procedure involves filing or grinding off part of the top tip of the firing pin until you get FTF. At that point, remove the ruined firing pin and replace it with a new factory pin as the OEM manufacturer designed. Calfee believed, in theory, that re-shaping the firing pin improved accuracy by directing the primer flash inward. In reality, the procedure only sells more firing pins.
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Old 07-08-2020, 12:44 PM
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Looking at the shells , the theory sounds good.
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Old 07-11-2020, 09:21 AM
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Quote:
Originally Posted by joet333 View Post
Re-shaping the firing pin is the very last thing you would do after trying everything else possible to improve accuracy, and you lay awake at night trying to think of something else to do. The procedure involves filing or grinding off part of the top tip of the firing pin until you get FTF. At that point, remove the ruined firing pin and replace it with a new factory pin as the OEM manufacturer designed. Calfee believed, in theory, that re-shaping the firing pin improved accuracy by directing the primer flash inward. In reality, the procedure only sells more firing pins.
Moving the hit inside the rim is so that you are guaranteed the pin will always strike primer upon contact when it hits and provide good ignition. having it hit the rim will not guarantee the pin's first contact will be primer and not brass.

Lee
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Old 07-11-2020, 09:32 AM
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Quote:
Originally Posted by horseman2 View Post
The firing pin was reshaped at my desk and the "pinprint" looked good testing with empties. At the range with Eley Match with a rim thickness of 0.036 there were two FTF out of four.
Tried CenterX which has a thicker rim and had one FTF our of five.
The pinpoint on the FTF rounds appeared to be more inside the rim when eyeballed.
Removed the firing pin and using one hammer as a makeshift anvil, six taps with the other hammer produced consistent ignition with all ammo tested and the pinprint in relation to the rim was more consistent. FTF's were eliminated and at 100 yards with Remington Eley Match 1062 a ten shot group measured 0.74 CTC.

I was always taken with blacksmithing but never thought I had the knack . . .
You shouldn't have had any ill effects from reshaping the pin, unless you filed the front of the pin too. I suspect reassembly of the firing pin into the bolt was the cause.
spring may have been dragging inside. this happens with Anschutz 54 on occasion.

You should also check how much the pin is off the stop. as the hits you show look a little light IMO


Lee
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  #11  
Old 07-11-2020, 11:02 AM
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Originally Posted by Hi-NV Shooter View Post
Moving the hit inside the rim is so that you are guaranteed the pin will always strike primer upon contact when it hits and provide good ignition. having it hit the rim will not guarantee the pin's first contact will be primer and not brass.

Lee

I went back and re-read Calfee's chapter on re-shaping the firing pin to improve ignition and accuracy. Although I agree with the theory, I have never seen anyone offer quantitative data to prove any gains or improvements comparing the re-shaped pin to the previous pin. Most of us do not have a sufficiently accurate rifle, equipment, bench technique, ammo or skill to see any improvements in accuracy. As for improving ignition, too often, people take too much material off the top of the pin resulting in FTF, then need to start over with a new pin. I have personally re-shaped several firing pins on various Kimbers with no improvements. These were sporters, not bench rest rifles. To me, the effort and results in re-shaping firing pins ranks right up there with weighing and sorting ammo by rim thickness.
Do it if it makes you happy. I'm still waiting to see someone offer proof of any improvements. I will gladly admit I'm wrong when I see the data.
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Old 07-11-2020, 03:13 PM
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Originally Posted by joet333 View Post
I went back and re-read Calfee's chapter on re-shaping the firing pin to improve ignition and accuracy. Although I agree with the theory, I have never seen anyone offer quantitative data to prove any gains or improvements comparing the re-shaped pin to the previous pin. Most of us do not have a sufficiently accurate rifle, equipment, bench technique, ammo or skill to see any improvements in accuracy. As for improving ignition, too often, people take too much material off the top of the pin resulting in FTF, then need to start over with a new pin. I have personally re-shaped several firing pins on various Kimbers with no improvements. These were sporters, not bench rest rifles. To me, the effort and results in re-shaping firing pins ranks right up there with weighing and sorting ammo by rim thickness.
Do it if it makes you happy. I'm still waiting to see someone offer proof of any improvements. I will gladly admit I'm wrong when I see the data.
Never read the book. on an average shooting rifle you would probably not see any difference. full blown bench setup may mean 1/4 bullet vertical.
same with firing pin springs, however with those you need to watch how hard the hit is.

Lee
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Old 07-11-2020, 06:47 PM
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Quote:
Originally Posted by joet333
Re-shaping the firing pin is the very last thing you would do after trying everything else possible to improve accuracy, and you lay awake at night trying to think of something else to do.
Change the word "accuracy" to "reliability", and you perfectly described my situation. I had even redesigned (and rebuilt) my Ruger mark pistol to be completely frictionless. And yet there were still failures to fire that could not be blamed on ammo lacking primer in the rim.

So I started with the Calfee firing pin design. It was pretty interesting. Reliability skyrocketed and accuracy tanked. Yeah, that's right - it TANKED!

That started a quest to find a shape that improved reliability to the same degree, but without hurting accuracy. I went through 5 or 6 designs before I determined the key elements. Every area hitting the back of the shell MUST BE square to the chamber face. This is where Calfee's firing pin design failed me. I can only believe it worked for him because he was testing in guns with match chambers. But they're just awful in guns with sporting chambers.

Second key is where the edge of the pin hits the case. This demands a FP that can't lift or shift around. It needs to hit the exact same place every time. Of course, minimal head space is a huge help also. Then the edge of the pin should be in line with the side of the case - NOT in line with the inside edge of the rim.

Most posts I've seen on FP shape show pics of the hit aligned with the inside edge of the rim. This has a tendency to squeeze primer into the powder and it's common to miss having some getting crushed. Moving the FP edge in to align with the case wall makes the back side "loop over" the priming mix to capture it. Then the primer is consistently crushed against the anvil.

CF and RF anvils are shown here by orange arrows:



Lastly, I also found a slight increase in accuracy by leaving a "cap" on the FP over the rim. If set so it only leaves a very shallow impression on the rim, it seems to help ensure the anvil is fully seated against the chamber mouth when ignition occurs. This shows what I have found to be the ideal FP strike:



So my sporting chamber pistol is not a real great yardstick for determining improvements in accuracy. But now with more than 30,000 consecutive rounds fired with no failures and reasonably good accuracy, it's a marvelous yardstick for reliability.
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  #14  
Old 07-12-2020, 10:57 AM
joet333
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Hi-NV Shooter and Test Engineer, thanks for the information above.
My take-aways are;
1. Don't read Calfee's book ( I now have a book for sale cheap) !!
2. Don't bother re-profiling the firing pin unless it's a full-blown custom bench rest rig.

Anything else?
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  #15  
Old 07-14-2020, 11:20 AM
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My take-aways are:

1) More than 99.99% of rimfire failures to fire are due to poor FP hits - NOT due an absence of priming mix in the rim.

2) Good FP shaping is always going to be a custom hand-fit job for an individual gun. It's got to be an iterative process - remove a teeny bit and test with live fire. (Hits on spent rounds will give false results.) Repeat until results are satisfactory.

3) You will probably mess up with your early attempts. It's easy to remove too much material. So have a couple spare FPs, go slow, and don't get discouraged.

4) The improvement in accuracy will NOT justify the effort for most shooters. But the improvement in reliability IS enough to virtually end needing any "alibis" in competitions.
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