Bushing firing pin?

M

Mram10

Guest
How important is it on the accuracy scale? Is there a good write up on how to do it? Is it worth it? Thanks
 
I would have thought that a custom benchrest action would be adequately machined & not require remedial work.
 
OP,
ream/install an oversize f/pin w/ .003" clearance to give you option(s).

A word of caution-
Do Not dry fire a 1/16" diameter f/pin.

There is also the venturi effect going from a .075" diameter to .062" diameter pin if one blanks/pierces a primer.
 
Dans40X said:
OP,
ream/install an oversize f/pin w/ .003" clearance to give you option(s).

A word of caution-
Do Not dry fire a 1/16" diameter f/pin.

There is also the venturi effect going from a .075" diameter to .062" diameter pin if one blanks/pierces a primer.
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Thank you. I was considering a sleeve and use the oem firing pin. Your way sounds easier
 
I have a Savage Long Range Benchrest in 6MM BR. It was cratering and giving off-center primer hits. Also, the accuracy had fallen off a good bit from its early years.

I sent the bolt to Greg and it came back quickly. No more cratering and no more off-center primer strikes.

Now, you can't send someone a bolt and expect the entire rifle to suddenly shoot a lot better. I have not spent the time to find the load, seating depth etc. that it wants now. However, I'm a step further along the road. I am happy with his services.
 
GeneT said:
Why is that? This is the first time I've heard that advice.

GsT
Click to expand...

They bend & break when turned straight.
There is/was a reason the firing pin had a taper from the stop shoulder to the tip.


Mram10,
Thank you. I was considering a sleeve and use the oem firing pin. Your way sounds easier.
Order a D.Holland oversize pin & ream the breech face for a few thousandths clearance....done.
Practice bushing the breech face,after you have seen a tutorial w/ pictures.

WSnyder,
I've never had to replace the firing pin on a J.Borden bushed bolt or firing pin.
 
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Dans40X said:
They bend & break when turned straight.
There is/was a reason the firing pin had a taper from the stop shoulder to the tip.


Mram10,
Thank you. I was considering a sleeve and use the oem firing pin. Your way sounds easier.
Order a D.Holland oversize pin & ream the breech face for a few thousandths clearance....done.
Practice bushing the breech face,after you have seen a tutorial w/ pictures.

WSnyder,
I've never had to replace the firing pin on a J.Borden bushed bolt or firing pin.
Click to expand...

Thanks. Will do
 
I've always wondered how the best way to bush a bolt was done. The Borden guide has been saved for future reference!
 
Years ago........

......I posted the following on the saubier(small caliber)board.

As a reference, and a good read, refer to Precision Shooting magazine, May 2001, page 31, "The Real Reason Primers Pierce" by Jerry Stiller.......you know....the guy who designs actions.

Hope this helps.

Kevin
 
Kevin Gullette said:
......I posted the following on the saubier(small caliber)board.

As a reference, and a good read, refer to Precision Shooting magazine, May 2001, page 31, "The Real Reason Primers Pierce" by Jerry Stiller.......you know....the guy who designs actions.

Hope this helps.

Kevin
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Thanks. No idea where I’d find that issue but I’ll google it
 
Kevin Gullette said:
......I posted the following on the saubier(small caliber)board.

As a reference, and a good read, refer to Precision Shooting magazine, May 2001, page 31, "The Real Reason Primers Pierce" by Jerry Stiller.......you know....the guy who designs actions.

Hope this helps.

Kevin
Click to expand...

Kevin, that article is great and has the engineering data to back up the small firing pin. Of course Dan is right. It is all futile if your firing pin is a sloppy fit.
 
Butch,

As far as blanking is concerned.....the article points to only the boltface hole diameter, as the primary culprit. I do agree that a good f.p./hole fit is good practice.....but unrelated to blanking.

This make any sense??

Anyway......my 2 cents.

Kevin
 
Kevin Gullette said:
Butch,

As far as blanking is concerned.....the article points to only the boltface hole diameter, as the primary culprit. I do agree that a good f.p./hole fit is good practice.....but unrelated to blanking.

This make any sense??

Anyway......my 2 cents.

Kevin
Click to expand...


I'm a little confused. I'm of the impression that a .062 firing pin in a fitted hole will prevent blanking. Excess headspace and a weak firing pin spring can contribute to this.
 
Butch........

Here's some more of my old posting on the small caliber board.

A little Jerry Stiller math.....

A 0.082" firing pin probably has an 0.084" boltface hole. The hole is 0.005412 square inches. At 50,000psi, this results in a total shearing force of 277.1 pounds.

Now use a 0.060" firing pin, with a 0.062" boltface hole. The hole is 0.003019 square inches. At 50,000psi, this gives a total shearing force of 151.0 pounds.

So.....for a 0.022" reduction in the boltface hole diameter, there is a 45.5 percent reduction in the shearing force.

As would be expected, a stronger firing pin spring has little effect.........been there, tried that.

Why these things only seem to happen with small rifle primers AND small calibers????.....I do not know, or can prove........but I strongly suspect that as the sectional density is lowered, a more "focused" pressure spike through the flash hole is created.....and the firing pin is pushed rearward. BUT.......that's just me.

BTW.....my old 20BR had about the same situation as above. Quite an eye-opening experience. Greg Tannel reduced the firing pin diameter, and bushed the boltface to a smaller firing pin hole size. The result.........with 40gr bullets blanking at 3400fps.........to NO cratering whatsoever at 4150fps.

Hope this helps.

Kevin
 
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