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SW mod 36 misfire

Discussion in 'Handguns: Revolvers' started by newbuckeye, Feb 28, 2012.

  1. newbuckeye

    newbuckeye Well-Known Member

    So I finally got to shoot the Model 36 I picked up a few weeks ago and every other round didn't fire. It looks like light strikes on the primer because when I continued pulling the trigger, all rounds fired the second time around. I even tried different brands to make sure it wasn't just a hard batch of primers (both factory loads).

    So, my question is, what needs to be changed to remedy a weak hammer strike? I really want to make the repairs myself (unless that is really discouraged).....

  2. Ron James

    Ron James Well-Known Member

    Once in another life, a friend and I worked for two hours on a family friends car on a cold and snowy Chicago night before I happened to check the gas gauge, yep, out of gas. Moral of the story, check the simple stuff first, It could be just the ammo, try a different brand, If that doesn't work then it is probably the hammer spring ( under the grip ). The previous owner may have cut a couple of links off to lighten the trigger pull in double action . Not a hard job to replace the spring. Oops, just read where you had tried different brands, all things being equal I think the mainspring is the main suspect
  3. XTrooper

    XTrooper Well-Known Member

    Before you change the spring, make sure the mainspring's strain screw is tight. The fix could be as simple as tightening it.
  4. rcmodel

    rcmodel Member in memoriam

    A model 36 is a J-Frame Chiefs Special.

    And they don't have strain screws.

    Only the Larger, K, L, N, and X frames have flat mainsprings and strain screws.

    All J-Frames have coil mainsprings.

    So, the 2nd. thing for the OP to do is replace the coil mainspring with a new S&W factory spring, or a Wolff 8.5 pound standard weight spring.

    http://www.gunsprings.com/Revolvers/SMITH & WESSON/J FRAME/cID3/mID58/dID263

    The 1st. thing for the OP to do is try different ammo.

  5. XTrooper

    XTrooper Well-Known Member

    I knew that! :D

    Thanks for catching my error!
  6. Jim K

    Jim K Well-Known Member

    Also, if the hammer has been "bobbed", that might cause lilght strikes. The hammers of J frames need all the weight they can get to provide enough momentum to touch off the primer; cutting off the hammer spur can reduce the weight (mass) enough to create problems.

  7. MrBorland

    MrBorland Moderator

    It's the opposite, actually. All else being equal, a lighter hammer increases reliability.

    Momentum may set primers deeper in the primer pocket, but it's not what lights off primers. Power does. A lighter hammer still has the energy stored in the spring, but it travels faster, so it imparts a more powerful strike on the primer.
  8. amd6547

    amd6547 Well-Known Member

    Excessive end play can also cause light strikes in revolvers.
  9. Nomad

    Nomad Well-Known Member

    IMO if you change ammo and it goes away you still have a problem. All ammo should be reliable. J-frames can be tricky with light strikes. If changing the spring doesn't make the problem go away I'd take it to a compitent gunsmith.
  10. newbuckeye

    newbuckeye Well-Known Member

    Thanks for the help! The hammer has been bobbed, but seeing as how it's birth date is about 1976, I hoped it was just a spring.
  11. hogrdr

    hogrdr Well-Known Member

    i had that problem with one of those about that time,70's, best i remember the firing pin hole through the frame was too small and wouldn't let the pin fall through easy enough.
  12. newbuckeye

    newbuckeye Well-Known Member

    I just ordered some wolff springs, so if that doesn't fix the problem I'll turn it over to an expert....
  13. PRM

    PRM Well-Known Member

    There are a couple of ways to correct that. There are some You Tube videos from MidWay that show using washers. OR, You can send it to S&W and have it done right. S&W replaced a frame stud (cylinder was jumping over it) and corrected the end shake on a Model 649 of mine last month for $62.00. They brought the gun up to factory specs for what I thought was a very reasonable price.
    Last edited: Feb 29, 2012
  14. Old Fuff

    Old Fuff Well-Known Member

    In that case, shouldn't a Colt Single Action Army revolver - that has the heaviest handgun hammer I can think of - need a heavier mainspring to insure reliability? In truth you can reduce it almost to the point where a hard look will cause the hammer to self-cock and it still goes BANG!!

    Years ago some research was done a Colt Government Model; proceeding in steps to see if reducing the hammer's weight by removing the hammer spur and more, to see if lock time was decreased. The answer was no, at least to the point where it became noticeable. If the hammer isn’t falling faster, where does the additional impact come from?
  15. Creature

    Creature Well-Known Member

    I can tell you from experience that a bobbed hammer does NOT increase reliablity in the Model 36. I purchased a bobbed hammer specifically for my Chief's Special and I experienced the exact same problem described by the OP. I tried several brands of factory new ammo to rule out the ammo being the problem. As soon as I re-installed the original hammer the problem disappeared.



    Same gun, different grips.
  16. MrBorland

    MrBorland Moderator

    Methinks it's a matter of hammer mass (or, more correctly, rotational inertia), relative to spring strength. Given a particular spring tension, the hammer can't accelerate any faster once it goes below some lower mass threshold. Given that one's finger doesn't have to work against the spring tension, it's possible that the SA guns you cite are oversprung compared to DA revolvers. If so, it's unlikely hammer speed will increase when hammer mass is reduced. Kinda like a bicyclist and a motorcycle each pulling a 25lb weight. The cyclist will certainly accelerate faster with every pound taken off, whereas you can remove the weight from the motorcycle entirely, with no noticeable effect on it's acceleration.

    J-frames benefit less from internal leverage, so they may be relatively oversprung as well (sure feels like they are), in which case speed won't increase, so you'll only get a net loss in oompf from the reduced mass.

    I should also point out that a lighter hammer has a lower rotational moment of inertia, so it resists spring tension less, and therefore accelerates quicker. But with that comes less resistance to the opposite forces of internal friction. If one's to benefit from a lighter hammer, all points of contact in the action have to be spot on; otherwise, yes, you can experience a net loss of reliability.
  17. newbuckeye

    newbuckeye Well-Known Member

    The spring pack i ordered had 3 different strength's so I will def be trying all of them to see what differences are there. I would like to stick with the bobbed hammer, but if nothing else fixes the misfires, then I will have to move onto other possible fixes.
  18. MartinS

    MartinS Well-Known Member

    Please let us know how it turns out and what made it right, Good Luck.

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