Quantcast

Firing pin extending too far out of bolt

Discussion in 'Gunsmithing and Repairs' started by Roamin_Wade, Feb 13, 2020.

  1. Roamin_Wade

    Roamin_Wade Member

    Joined:
    Mar 23, 2019
    Messages:
    159
    Location:
    TEXAS
    I have an old rifle that I’ve yet to shoot. The firing pin sticks out between 1/10” to 1/8” from bolt face. How far is too far? See pics below. Thanks!
     

    Attached Files:

  2. boom boom
    • Contributing Member

    boom boom Contributing Member

    Joined:
    Sep 24, 2007
    Messages:
    3,828
    Location:
    GA
    What is the make of the rifle because this makes a difference? Is it a Mauser--you appear to have two forward locking lugs and a rotating xtractor? For a Mauser 98 action, the firing pin protrusion is .055 - .065

    I use this little device to measure it as it is more exact than other methods. https://www.brownells.com/gunsmith-...fire-firing-pin-protrusion-gauge-prod867.aspx
     
    Slamfire likes this.
  3. Shimitup

    Shimitup Member

    Joined:
    Feb 27, 2009
    Messages:
    954
    Location:
    Houston
    You should take that apart and give it a closer look, that's not right. I don't know exactly how far it should stick out but I'm guessing about .025 to .030 more or less. I doesn't look radiused either. I'm wondering if somebody has been hacking on that gun.
     
    Last edited: Feb 13, 2020
  4. Scooter22

    Scooter22 Member

    Joined:
    Apr 2, 2012
    Messages:
    1,915
    Location:
    Central NY, not the rotten apple
    That looks too far and might pierce primers.
     
  5. Slamfire

    Slamfire Member

    Joined:
    Dec 29, 2006
    Messages:
    10,287
    Location:
    Alabama
    I think the primary concern is piercing primers. That firing pin is further out than any I have ever seen, you need to check the cocking piece and make sure you don't have a problem that might turn into this:

    4CSzEo0.jpg

    3JNbfiC.jpg

    6nrnVHf.jpg
     
    boom boom and Shimitup like this.
  6. Roamin_Wade

    Roamin_Wade Member

    Joined:
    Mar 23, 2019
    Messages:
    159
    Location:
    TEXAS
    It is a Savage model 1920 and it is a Mauser action.
     

    Attached Files:

  7. Roamin_Wade

    Roamin_Wade Member

    Joined:
    Mar 23, 2019
    Messages:
    159
    Location:
    TEXAS
    I unscrewed the cocking piece one turn and now it sticks out far less. Almost not enough. Is there a minimum that a pin has to protrude?
     

    Attached Files:

  8. Alaskan Ironworker

    Alaskan Ironworker Member

    Joined:
    Feb 5, 2018
    Messages:
    529
    Location:
    Wasilla
    Read what boom boom said. .055-.065. You can also check protrusion with a cheap automotive feeler gauge. The minimum it can protrude will be the line where your gun begins unreliably detonating primers, and the max is when it pierces primers.
     
  9. Slamfire

    Slamfire Member

    Joined:
    Dec 29, 2006
    Messages:
    10,287
    Location:
    Alabama
    I don't know if I have held a Savage M1920, that is a rare rifle. I have no idea if you are missing parts that maintained proper firing pin protrusion.

    As @Alaskan Ironworker said, measure the protrusion, but I will say, the second set of pictures looks better than the first.
     
    Roamin_Wade and boom boom like this.
  10. boom boom
    • Contributing Member

    boom boom Contributing Member

    Joined:
    Sep 24, 2007
    Messages:
    3,828
    Location:
    GA
    Okay, you have a threaded firing pin which Mauser itself quit using after the 91 Argentine Mauser model. That makes it a bit easier to adjust fp protrusion.

    The actual protrusion needed will depend on headspace, your firing pin spring strength, cocking piece wear, the hardness or lack thereof of the primers, and avoidance of risking pierced primers by too great a protrusion. I am leaving out the firing pin weight which also affects this as this is constant. If you do have cocking piece problems, you will generally have problems applying the safety if the Model 20 follows the std. Mauser design. I have such a problem now with a 91 Argentine Mauser rebuild where I had to use an aftermarket replacement firing pin as the original broke. The firing pin and cocking piece go too far forward and as a result, the safety will not apply but the rifle will fire (have tried to fit a variety of sears, triggers, bolt sleeves, safeties for it, and cocking pieces so the problem has been isolated to the replica firing pin length). Solution then is a new firing pin which I prefer to be original this time instead of the gpc replica which had some other issues like firing pin tip softness.

    One of the big things that can affect actual ignition is worn chambers allow the brass to move forward (worse with extractor wear) and the cartridge moving forward before firing basically reduces firing pin protrusion. As a result, a lot of folks 'adjust' their firing pin protrusion to get reliable ignition with a worn chamber instead of setting back the barrel and requalifying it. Given the age of the rifle, it is certainly possible that someone did just that especially with the threaded firing pin. I would check the headspace of your rifle first. If the headspace is within the no-go range and the extractor holds the brass tightly to the bolt head, then you can work the math back to determine the needed firing pin protrusion. Some folks have reported that at least .050 firing pin protrusion is a minimum for Mausers in general but a lot depends on whether Savage followed Mauser specifications.

    You might try calling Savage as they might have the specs and that would save a lot of grief or posting on a Savage collector's forum and maybe some kind soul has had your problem. Model 20's are pretty rare and some owner might even check their own rifle for protrusion and report back to you.

    Otherwise, you might need to do trial and error which can be a drag. To do that safely, you can use primed cartridges with no powder or bullet and set the fp protrusion at the minimum and proceed to lengthen the firing pin protrusion turn by turn until you get reliable ignition. The danger is that you might get a pierced primer that throws hot gas back at you so you will need to wear protective gear to do this.

    I have not tried this but seen this described in old timey gunsmith manuals. The other would be using some material in a brass empty case that would deform and hold the firing pin impression--this can give misleading information because you will get some spring back in most materials after initial deformation. Maybe filling the cartridge primer pocket with a soft metal or deactivated primer which you would still need to do safety precautions might do it. But after you did this to get an initial set, you would probably still need to confirm it with live primer test above.

    My military rifles, pretty much, have published specifications or other shooters have posted their trial and error results, so that I only have a few old blackpowder cartridge rifles that I worry about finding out the best firing pin protrusion length.

    Here is Larry Potter of Midway explaining fp protrusion
     
    Alaskan Ironworker likes this.
  11. Roamin_Wade

    Roamin_Wade Member

    Joined:
    Mar 23, 2019
    Messages:
    159
    Location:
    TEXAS
    I used my calipers to measure how proud the Firing pin is now and I’m getting .020”-.025” only. You think that is enough?
     
  12. boom boom
    • Contributing Member

    boom boom Contributing Member

    Joined:
    Sep 24, 2007
    Messages:
    3,828
    Location:
    GA
    I would think that is not enough but without the specs of your rifle, it might or might not be. That leaves trial and error approach with something to measure the primer strike depth or calling for Savage/Savage collector forum help. Mausers generally run .055-.065 and supposedly Peter Mauser felt that less than .050 would not work. But, yours is a variant so it might or might not work--do though check the headspace because if the pin was like that when you got the rifle, it was that way for a reason--my guess is too long headspace or it could be that someone disassembled the bolt and then didn't put it back together the way it was.

    Once I get the firing pin protuberance set to what I want, I generally mark across them so that you can tell if it has moved. Liquid paper or fingernail polish can do it or the Russians used to strike a mark across the cocking piece with and firing pin with a punch.

    Another checking method of firing pin strike is this.
    You can theoretically dampen or even deactivate a primer by soaking it in oil. Check the reloading forum for the exact length of time required. Doesn't always work totally but that would be another alternative to a live primer test in an empty cartridge and if it fired, it would more likely be a squib primer but still use protective gear and an empty cartridge sized to length. You can do check the firing pin strike on the dead primer with a depth gage but usually easier to eyeball it for the firing pin strike.
     
    Roamin_Wade likes this.
  13. Blue68f100

    Blue68f100 Member

    Joined:
    May 25, 2011
    Messages:
    5,411
    Location:
    Piney Woods of East Texas
    Does not work since the primer compound have a sealer on them. Only way that is 100% is to fire them off. Do wear hearing protection but it will not be bad in a rifle. I've only have had 1-2 bad primers in 40+ yrs of hand loading. One was missing the anvil, the other the primer compound pelt. It's a very rare thing to get bad primers. You can get primers where the cup is weak/bad which will cause primers to pierce, eating up the breach face.

    You may be able to remove the sealer, but once the compound dries out it will be active again. Best to just set them off. Just be careful in how you do it for they have a lot of energy.
     
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice