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Savage 1907 Hammer (Striker) Follow

Discussion in 'Gunsmithing and Repairs' started by Johnm1, Jul 19, 2020.

  1. Johnm1

    Johnm1 Member

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    I do appreciate firearms that are 'different'. I'm not sure this one tops the H&R Self Loading 25, but it is close. NOTE: there is not a single screw in the entire firearm. Including the grip panels. So, on to the story.

    The title describes the problem. The striker follows the slide forward if the slide is operated energetically. It will remain cocked if the slide is operated slowly. Here is a diagram of the gun in question as well as a picture of the gun partially assembled. Operation is not intuitive. If you are interested in seeing how it works this video shows the operation very well. This pistol functions like the video except the striker follows.



    Here is a diagram of the gun. The part numbers involved are 11 and 14.

    1907_exploded_view1.gif
    1907_exploded_view2.GIF

    Her are some pictures of how the sear (11) mates with the frong of the firing pin (15).

    IMG_2105.JPG

    IMG_2106.JPG

    IMG_2107.JPG

    And here is a picture of the sear tripped by my thumb. The part that is raised is the part that mates with what should be a square edge on the firing pin that mine has the 'sloped' feature.

    In the Un-Tripped Position
    IMG_2108.JPG
    In the Tripped Position
    IMG_2109.JPG

    And here is the offending Firing Pin with the slope apparently ground into it.

    Firing pin.JPG

    This is what it should look like. I'll assemble tomorrow to confirm this cures the hammer follow.
    Pin 2.PNG

    EDIT to add a better picture of what the surface should look like:

    Better picture of correct firing pin.JPG
     
    Last edited: Jul 19, 2020
  2. Johnm1

    Johnm1 Member

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    I had a bunch of work to finish for my job today and didn't get to reassembling the Savage 1907 yet today. During my breaks from my real job, I looked at the new firing pin compared to the old. Not only does the old firing pin have what I believe to be a 'slope' cut in incorrectly after the fact I notice that at the location there is a flat spot on the firing pin to allow the sear to sit 'further down' the face of the firing pin that isn't on the replacement firing pin. It is difficult for me to get good close up photographs, so bear with me and my photographs. They aren't good, but in general they show what I want to talk about.

    Here is the picture of the original firing pin as shown in the above post. Here you can see the slope but right underneath it there is a 'flat spot' machined into the round portion of the firing pin.

    Flat Spot.JPG

    Here you can see that there is no corresponding flat spot on the replacement piece. I did check all around though the pin can only be installed in one of to positions due to the pin hole in the back of the firing pin.

    1.JPG

    It seems to me that the flat spot provides a little more 'purchase' for the sear to work against. See this picture of the sear in position on the firing pin.

    4.JPG

    So, if I put the flat spot on the new firing pin I believe that the sear will have more surface area touching the vertical face of the firing pin and be less subject to 'slipping off'. Would you agree?

    FYI - I will assemble the unit without putting the flat spot in and testing for reliably holding the sear. If it works on my bench I'll do the same in a function test in the field. If either fail, I think I'll put the flat spot on the firing pin. But I'd like your opinions on the usefulness of the flat spot. I suspect that fabrication changes over the years of production might account for the differences in the firing pins. Also, I got the replacement firing pin from Jack First and his pictures of his firing pins lead me to believe that he may well have OEM replacement firing pins that have never been fitted to a gun. That too could explain the differences. Or, the flat spot could have been put there by the person who ground the slope into the firing pin.

    FYI - the pin/spring combination are held in place by a pin through the cocking piece (looks like a hammer). So the original pin could be rotated 180 degrees and that surface made for the sear bearing surface. Does that make sense?
     
  3. BBBBill

    BBBBill Member

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    I wouldn't cut anything until I thoroughly tried/tested it. Maybe not the best example, but the 1911 hammer/sear relationship in GI spec and older commercial guns is as much as .030 engagement, but can function reliably with very minimal engagement. In a tuned gun that is typically discussed as being .020" engagement, but the actual amount is usually lower than that due to the escape angle cut on the back edge of the sear. The sear and hammer hooks do not mate in a flat plane to plane relationship, rather the tips of the hammer hooks land on the sear face. So the contact is basically .0000000....001". Now the geometry of that is critical when tuning to that level and is very different to what you have with the sear/striker in that gun. The spring force exerted is likely very different, too. I've seen many fail due to bad parts and/or bad tuning. So prove what you have first and proceed with caution when making changes. Heck, the angled slope and flat spot might be the result of normal factory fitting and either the same on every gun or exclusive to each gun. With the lack of available smithing info you might never know.
     
  4. Johnm1

    Johnm1 Member

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    I understand what you are saying Bill. My intent is to put everything back together again without changing a thing other than I did get a new sear spring and I figure I should replace it just because I'm there and I have no idea how old the original sear spring is. And for all I know, the sear spring is the problem and the slope and the flat are as they left the factory. My assumption that the slope was a Bubba job is just that, an assumption.

    Before I do anything, I do posses the same model in 32 ACP manufactured a year later and I think I'll take the breach bolt apart just to see how it is arranged. I cannot see the engagement of the sear/firing pin with the breach bolt assembled. Fortunately I did find the instructions on how to disassemble the breach bolt in this book "Firearms assembly II, the NRA guidebook to handguns".

    Assuming there are no epiphanies found inspecting the 32 version I would start with replacing the sear spring and leave the original firing pin as is. Bench and field test and if that doesn't work, then move on to the firing pin in its as arrived condition. Bench/field test and if that doesn't work start looking at the flat. The more I think of it, the sear spring could be the problem. It forces the sear down in front of the firing pin and if it is weak it could release the sear even if were properly engaged. lack of available smithing info is a real issue here. Unlike the 1911 you mention, there isn't anyone alive who is a real expert on these things. Maybe there are some other 'tinkerers' like me, but the people who knew about these guns all died over 50 years ago.
     
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  5. Johnm1

    Johnm1 Member

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    Well, we have success!

    At least until I can get this one out to the range and function test it with live rounds. I suspect the function test with live rounds will confirm success. But the slope on the firing pin was the cause of the hammer follow. At first I replaced only the sear spring but that did not cure the hammer follow. Next I turned the existing firing pin 180 degrees and took the slope on the pin out of the equation. That worked at least when cycling by hand. And cycling by hand had a 100% failure rate previously unless you cycled it gently. And, the trigger pull isn't bad. I was afraid that by removing the slope I'd end up with a 15 pound trigger pull. Not sure what it is, but it is sufficient for a 380 defensive pistol with tiny sights. Man I wish they had made any of these old guns with decent sights. Heck, the 25 I'm working on doesn't even have sights. Talk about being honest about expectations.

    I did look at the same surface on the 32 version of the same pistol and the sloped surface was not there. So I figured replacing, or in this case reversing, the firing pin would cure the problem.

    This is actually the second success story I've had bringing an old pistol back to useful life. Earlier this summer I repaired an Iver Johnson Supershot top break 22 revolver that had a bent cylinder arbor. Actually I had my gunsmith bend it for me most of the way and I tweaked the final adjustments. It started out with a 4" plus group at 10 yards and spit lead. I ended up with a 1 1/2" group at 11 yards and I'm not sure that isn't about as good as I can see the sights. I really like that revolver as it just matches my personality.
     
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  6. Johnm1

    Johnm1 Member

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    I field function tested the Savage 1907 380 today. It functioned flawlessly. I would call it self-defense accurate at 7 yards. I didn't try any further. The trigger pull was quite good. This is the end of this story.
     
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