Firing Pin Bushing -- When Needed, Specs?

[Forum Boss]

jb1000br
1000yd Editor

When you guys get pins bushed, what clearances and diameters are used.

.001 clearance with .062-.065 pin????
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DANTEC
Charter Member

Clearence is direct linked to firing line / bolt cocentricity if you firing pin shroud thread is crooked, ofcenter or most commun on Rem bolt not coaxial ) you get brake effect when you reduce firing pin clearance

first step is to check firing shroud tead and blue print when possible or find a good bolt body

0.001 is ok but you can also let the front diameter, firing impact aera with 0.001 ) and increase a bit on the rear to allow less conatct in bushing

carefful check protusion too and carefful check bumping aera inside the bolt to be sure where your firing pin stop, not a BIG BURR as example )

DAN TEC
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lynn
Charter Member

Jason
You might ask Mike Bryant as he bushed one for me to 0.0625 but i have no way of measuring the fit accurately.It appears to have zero clearance in the fired position but it could be my eyes and the lighting in my gun room.
Lynn
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Al Nyhus
Charter Member

Hi Jason. Assuming that the pin is traveling straight down the bolt i.d., you can run with a small as .001-.002 clearance.

Another thing to watch for...make sure the pin isn't retracting beyond the rear of the bolt face when it's cocked. This is more common that people realize. When the pin drops in this scenario, it bounces it's way through the pin hole, setting up all sorts of McNasty vibrations. I've seen Stan Ware at SGR make up some 't' shaped bushings to help guide the pin in these situations.
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jb1000br
1000yd Editor

well, greg tannel only has .0005 clearance i have found!! the action i have coming will have .001 clearance, so we shall see.
Al, i'll see how the action does first, but will keep stan in mind should problems arise.
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Al Nyhus
Charter Member

JB....I wanted to post the .0005 figure, but didn't think anyone would buy it! HaHaHa! The 't' shaped bushing is pretty commonly done by most accuracy 'smiths....Gre-Tan, Borden, SGR, etc.

On our Stolles, we like to see it around .001 and this is how they measure out-of-the-box.

Best of luck with your project. By the way, what action are you using? -Al
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jb1000br
1000yd Editor

Al--I knew you'd ask that, but I cant give that up yet, as it is not set in stone, and not really available--yet! You will see it in the spring when i get all my parts assembled and load development done

JB

hopefully all goes as planned

 

[LeoAhearn]

Question - is bushing the only option, or can an oversized firing pin be fit to the existing hole with low clearance and accomplish the same thing?

 

[jb1000br]

Leo--why? It only costs 40$ to get the pin turned to 0.062 and bushed

seems an oversize pin and fitting work would cost similar or more, and you are still stuck with a BIG pin.

Big hole/pin, small primeris not the best solution.

JB

 

[vmthtr]

Leo,
No the bigger pin does not do the same thing. Jerry Stiller wrote a great article on it and here is an example of why primers sheer. Put paper over a 5 gallon pail and push in the center, and then take the same paper and put it over a soda can and push in the center. Strength of primer are the same, but with a smaller area unsupported, is stronger the smaller you get.

Mike