• Firing Pin Protrusion Data.

    Here are some data points I think are useful and could be incorporated as a sticky. Since there have been a lot of recent discussions about firing pins, I thought I'd consolidate different data in one thread.

    Quote Originally Posted by sharpshooter View Post
    First off, you are never going to "puncture" a primer no matter what the protrusion is set at, unless of course the pin tip has a sharp point.

    The tip of the firing pin will never indent the primer over about .025". It will bottom out on the anvil of the primer. Typically the protrusion is set from the factory at about .055", which is plenty long and all it does is limit the firing pin travel, giving less impact energy. .035" is optimum.
    To measure firing pin protrusion, use the depth measuring rod on the butt end of a set of calipers, put the calipers on the rim of the bolt face, then set your zero on either the bolt face or the firing pin, and then measure to the firing pin or bolt face (whichever you did not use to set zero).
    Here's a great picture taken by Blue Avenger:

    Quote Originally Posted by Blue Avenger View Post
    Quote Originally Posted by thomae View Post
    The firing pin threads (at least the large diameter one that is in pieces on my workbench) are 28 TPI.
    By doing the math, we find that when you adjust the firing pin, each quarter turn of adjustment equates to a change in protrusion (either more or less depending upon which way you turn) of 0.00893". One full revolution equates to a change in firing pin protrusion of 0.035714"
    To adjust firing pin protrusion, you need to be able to compress the firing pin spring in order to adjust the firing pin protrusion by turning the firing pin stop nut.
    I had an idea for making a Firing Pin Adjustment Tool, but Blue Avenger posted a photo showing a much better/simpler idea: Use a standard set of wire strippers/crimpers as shown in the following photo:

    Quote Originally Posted by Blue Avenger View Post
    Quote Originally Posted by sharpshooter View Post
    After you set the FP protrusion, install the spring and the lock washer, then compress the spring and thread the cocking piece on. Adjust the cocking piece until the spring is compressed to a length of 1.900" for a short action, 2.600" for a long action.


    DISCLAIMER:
    The information contained in this article and the attached video are for educational purposes only. Should you choose to use this information to alter or modify your firearm you do so of your own accord. In doing so you accept full responsibility for any adverse affects, damages, injuries and/or death that may occur as a result.


    Comments 5 Comments
    1. louielouie's Avatar
      louielouie -
      Following this method I originally had about 0.060 protrusion. Using about a 1/4 turn I reduced protrusion to 0.050. The problem was cratering of primers (Federal 210M which didn't crater before) since there must be some wear in this well-used rifle. I may need to consider a new bolt head. I just carefully polished the tip and put everything back the way it was, for now.
    1. memilanuk's Avatar
      memilanuk -
      The problem may not be firing pin protrusion so much as an oversized hole vs. the pin. Might send it to Gre-Tan Rifles to have the firing pin hole bushed, the pin turned to size and the hole reamed to match. Minimal gap all the way around will likely cure any primer cratering issues you might have had. Their turn-around time is excellent... used to be about a week to ten days there and back.

      HTH,

      Monte
    1. Dennis's Avatar
      Dennis -
      It's hard to see in your pictures, but on my caliper, on end a bar protrudes out/in that will give you the exact measurement.

      If necessary, I will take a picture and email it to you if you email you info.

      Dennis
    1. Ratbuster's Avatar
      Ratbuster -
      Ben Chappell does high quality bushing jobs on Savage bolt heads for $40 with super quick turn around time. He has done 2 for me and for two other friends of mine. He will set the clearance tight for a bench gun or slightly looser for a field gun that sees more dirt and less cleaning. Will eliminate primer cratering.

      You can find him on Accurateshooter.com forum. Do a search for "Grimstod"
    1. Robinhood's Avatar
      Robinhood -
      I agree on Grimstod. But first I would measure the pin and the hole in the bolthead.