Bill Calfee
Gun Fool
Firing pin spring pre-load.......
CYA friends:
You know, after all these years posting on and viewing these rimfire accuracy Internet forums, I don't believe I've ever posted, or read, about the subject of firing pin spring pre-load.
Until I started posting about how I was getting beautiful, Turbo consistent ignition on this new DiOrio V-3 with only 8 pounds of firing pin spring pre-load.
I bring this up, because friend Jsmith, on another thread, posted some excellent, and very interesting comments about firing pin spring pre-load.
It seems that too little pre-load, however much too little is, may cause firing pin bounce.
_____________________________
This brings up a very interesting series of questions.
The most obvious being, what the minimum firing pin spring pre-load that is necessary, to be able to produce Turbo class, rinfire ignition consistency.
CYA friends, when I use the term "Turbo class", I'm referring to well blueprinted, MD-PAS ignition which is capable of producing 10-0 case head penetration runs.
And 10-0 is all we can obtain......I'm not aware there is a better number than zero.
_________________________
So again, what is the least amount of firing pin spring pre-load, that will allow a MD-PAS action to produce 10-0 case head penetration runs?
I believe, think, I can speak from experience here....
8 pounds of firing pin spring pre-load, will produce 10-0 case head penetration runs in this new V-3.
With absolutely no firing pin bounce.
So what is the actual lower limit?
Your friend, Bill Calfee
___________________
PS:
CYA friends:
I know the ole Hawk, Tom Wilkinson, the ole Mule Skinnah, Jeff Patterson and probably others, when they saw this picture, knew that I had not finished this firing pin tip.
Which I haven't, on purpose.
I diamond filed this V-3 tip down from .050" to .033".
And I left it, as filed, so the edges of the pin tip were sharp.
When finished, those sharp corners will be slightly rounded, not sharp.
I do this, because with the sharp edges, if the pin double strikes, bounces, with a loupe I can usually see where the sharp edged pin tip scrapes the side of the original footprint when it recoils backward, and then sits back down.
Not always......
Sometimes a bouncing pin will bounce, and then torque twist before it sits back down...
When it does this, it leaves a very obvious "double strike" in the foot print.
Somewhere I've got a picture of a double strike produced this way.......
It looks like one re-cocked the bolt, then snapped on the same case again.....
But both strikes were produced with one firing.
______________________________
There is no bounce in this footprint.....with only 8 pounds of pre-load.
Notice how sharp the edges of the footprint are.
This pin tip is unfinished....
And if you look closely, you can see there's no secondary pin scraping, like happens when the pin recoils, bounces, then sits back down....( although this is not a completely foolproof indicator, but works about 90% of the time, at least)
______________________
Look very closely, there is no secondary scraping that a bouncing pin would produce....(at least 90% of the time)
________________________
And something else, there's a couple more ways I know this pin is not bouncing....even at 8 pounds.
I'll describe them shortly....bc
______________________________
One other thing before I stop....
I've stated that we're in uncharted waters with this new V-3....
I don't know yet whether it's clever design by Anthony DiOrio, or blind luck....
But this V-3 is doing things that I've never seen before......ever....
CYA friends:
You know, after all these years posting on and viewing these rimfire accuracy Internet forums, I don't believe I've ever posted, or read, about the subject of firing pin spring pre-load.
Until I started posting about how I was getting beautiful, Turbo consistent ignition on this new DiOrio V-3 with only 8 pounds of firing pin spring pre-load.
I bring this up, because friend Jsmith, on another thread, posted some excellent, and very interesting comments about firing pin spring pre-load.
It seems that too little pre-load, however much too little is, may cause firing pin bounce.
_____________________________
This brings up a very interesting series of questions.
The most obvious being, what the minimum firing pin spring pre-load that is necessary, to be able to produce Turbo class, rinfire ignition consistency.
CYA friends, when I use the term "Turbo class", I'm referring to well blueprinted, MD-PAS ignition which is capable of producing 10-0 case head penetration runs.
And 10-0 is all we can obtain......I'm not aware there is a better number than zero.
_________________________
So again, what is the least amount of firing pin spring pre-load, that will allow a MD-PAS action to produce 10-0 case head penetration runs?
I believe, think, I can speak from experience here....
8 pounds of firing pin spring pre-load, will produce 10-0 case head penetration runs in this new V-3.
With absolutely no firing pin bounce.
So what is the actual lower limit?
Your friend, Bill Calfee
___________________
PS:
CYA friends:
I know the ole Hawk, Tom Wilkinson, the ole Mule Skinnah, Jeff Patterson and probably others, when they saw this picture, knew that I had not finished this firing pin tip.
Which I haven't, on purpose.
I diamond filed this V-3 tip down from .050" to .033".
And I left it, as filed, so the edges of the pin tip were sharp.
When finished, those sharp corners will be slightly rounded, not sharp.
I do this, because with the sharp edges, if the pin double strikes, bounces, with a loupe I can usually see where the sharp edged pin tip scrapes the side of the original footprint when it recoils backward, and then sits back down.
Not always......
Sometimes a bouncing pin will bounce, and then torque twist before it sits back down...
When it does this, it leaves a very obvious "double strike" in the foot print.
Somewhere I've got a picture of a double strike produced this way.......
It looks like one re-cocked the bolt, then snapped on the same case again.....
But both strikes were produced with one firing.
______________________________
There is no bounce in this footprint.....with only 8 pounds of pre-load.
Notice how sharp the edges of the footprint are.
This pin tip is unfinished....
And if you look closely, you can see there's no secondary pin scraping, like happens when the pin recoils, bounces, then sits back down....( although this is not a completely foolproof indicator, but works about 90% of the time, at least)
______________________
Look very closely, there is no secondary scraping that a bouncing pin would produce....(at least 90% of the time)
________________________
And something else, there's a couple more ways I know this pin is not bouncing....even at 8 pounds.
I'll describe them shortly....bc
______________________________
One other thing before I stop....
I've stated that we're in uncharted waters with this new V-3....
I don't know yet whether it's clever design by Anthony DiOrio, or blind luck....
But this V-3 is doing things that I've never seen before......ever....
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