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Where to measure end shake

Discussion in 'Handguns: Revolvers' started by mr.ridout, Nov 27, 2018.

  1. mr.ridout

    mr.ridout Member

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    Should end shake be measured from the back of the bullet casing or the back end of the cylinder. If the cylinder has a snug fit, say .002" end shake, but there is .020" behind the casing, then surely the casing is going to slide back and hit the frame with each firing. I have a lot of space behind the casings, maybe .095". I can make a washer shaped fitting of about 1" outside diameter that will hold all six cartridges tightly in the cylinder or a crescent shaped fitting that will fit behind the casing lined up with the barrel and ramp up to that point.

    Can anyone follow what I am trying to say here? What do you think?
     
  2. Vern Humphrey

    Vern Humphrey Member

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    End shake is the fore-and-aft movement of the cylinder under recoil. You can hold the gun in your hand and try to wiggle the cylinder back and forth and actually feel end shake. To measure it precisely, clamp the gun by the barrel in a padded vise and move the cylinder back and forth. Use feeler gauges to measure maximum and minimum gap and subtract to get the actual end shake.

    You can buy bearings -- flat little metal rings from places like Brownells. Select the thickness that corresponds to the measured end shake, and remove the cylinder and unscrew the base pin. Place the bearings into the recess on the front of the cylinder, lube and reassemble.
     
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  3. mr.ridout

    mr.ridout Member

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    Yes, I know what end shake is. And "actually feel it?" I can see it. 95 thousands is not hard to see. I can't move the cylinder back with bearings. It would leave a huge gap between the cylinder and the barrel.... .095". I have to space it up from the back, which means that I must space it in such a way that the casings are held forward as well as the cylinder. If I don't then the casings will kick back more than 1/16" when fired.
     
  4. beag_nut

    beag_nut Member

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    To answer your original question: End shake is measured from the front of the cylinder to the back of the barrel. Not from the back of the cylinder. If you can move the cylinder fore and aft .095 then something is seriously wrong.
     
  5. 243winxb

    243winxb Member

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    No idea how to fix case head to recoil shield clearance, other then setting the barrel back 1 turn. I am thinking some slop is normal? Never checked that end.

    What make and model revolver?
    Does the gun misfire? Firing pin not reaching the primer?
     
    Last edited: Nov 28, 2018
  6. RKRCPA

    RKRCPA Member

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    What kind of revolver is it? If you have that much space behind the case heads with the cylinder forward that is a headspace problem.
     
  7. mr.ridout

    mr.ridout Member

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    Maybe not so much seriously wrong as seriously worn. It is a Belgian copy of a S&W DA .44 about 140 years old. I'll bet it would misfire or who knows what if I loaded it and tried (which I am not going to do right away). I would prefer to add some to the barrel, but there just isn't enough meat in the back end of the barrel to do that. So short of cutting the frame, which I will not do, or adding to the cylinder, which I cannot do, I will have to add something to the frame.
     
  8. 243winxb

    243winxb Member

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    How much firing pin protrusion? I am guessing not enough. Many guns are around .055"
     
  9. mr.ridout

    mr.ridout Member

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    The pin is part of the hammer and the protrusion is .067". I have tested it with a spent cartridge with a piece of tape on it and it went through the tape, so does hit. As it is now, I would think that the pin would take the brunt of the casing recoil and maybe break off the point.
     
  10. Varminterror

    Varminterror Member

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    That is supposed to happen...
     
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  11. 243winxb

    243winxb Member

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    Hammer bounce can be seen in slow motion videos when firing revolvers.

    I guess it could break??
     
  12. Varminterror

    Varminterror Member

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    The firing pin is designed to hit the primer, so having primers hit it back is not an issue.

    I really would like to see a photo with 95 thou of shims behind the cases when chambered. You’re talking about ~150 thou of gap between the cylinder face and recoil plate. Are you measuring that 95thou with the cases in place? And you are measuring at the recoil plate, not the recoil shield? Are the chambers recessed to engulf the case rims?
     
  13. jamesjames

    jamesjames Member

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    I have one of these Belgian-made .44 revolvers. Smith #3 DA top-break. Those made in Spain or elsewhere were pretty loose revolvers chambered for .44 Russian. The fit and finish on mine is poor. I've contemplated a restoration project but think it is a gunsmith project. above my pay grade.
     
  14. beag_nut

    beag_nut Member

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    I think pics are seriously needed here, considering how uncommon and weird the stated problem is. And the pics need to be current.
     
  15. mr.ridout

    mr.ridout Member

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    Sorry guys. I just can't figure out how to get the pics from my iphone into the computer. As soon as I do I will put some up. In the meantime, I will say that .095" space is without cartridges installed. I think they have about a .060 thick rim, so we are talking about .035" head space. So I guess I need to deal with about a 32nd of an inch. That doesn't seem like much, but I would still like it to be gone.
     
  16. beag_nut

    beag_nut Member

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    You do not yet seem to understand that end shake (as you described it) has nothing to do with the rear of the cylinder. Rather, it is the space between the front of the cylinder and back of the barrel. One simply pushes the cylinder forward and uses a feeler gage to get a reading. Then, one pushes the cylinder back (toward the grip) and takes another feeler gage to measure the same gap. The difference between the two readings is the end shake. The distances at the rear of the cylinder have nothing to do with end shake, except as a relative value. The end shake also has nothing to do with the cartridges.
     
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  17. mr.ridout

    mr.ridout Member

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    Sorry, but I do know what end shake is. And if you have a certain gap between the cylinder and the barrel when pushed forward, then you have the same gap between the cylinder and whatever stops it at the rear where it hits the frame. If it didn't have that relation, then all I would have to do is put enough bearings at the front to take up the excess space. If I did that then there would be a huge gap between the cylinder and the barrel, which is unacceptable. And I understad that it has nothing to do with the cartridges, except that with them in, they stop the rearward movement. With them out, the cylinder will go back so far as to leave about .095" between the cylinder and the barrel. And I don't see why I cannot reduce headspace and end shake by adding to the rear of the cylinder center.

    Oh,..... and I described the gap as .035" headspace.
     
  18. Vern Humphrey

    Vern Humphrey Member

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    That's exactly right.. You can get them from Brownell's.

    .

    If you consider it unacceptable, the only cure is to FIRST deal with the end shake using bearings, as described above, and then to set the barrel back one thread. However, since the end shake cure is quite cheap, I'd shoot the gun afterwards and see how it performs. You may not need to set the barrel back.
     
  19. 243winxb

    243winxb Member

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    So, the firing pin will reach the primer, plus a little extra. I dont see a problem? Or did i miss something?
     
  20. mr.ridout

    mr.ridout Member

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    So this depends on what I consider unacceptable. I would not have given it much thought until I looked at it and it seemed excessive. So I watched some video on youtube of firing a revolver with a large gap. The blast shredded paper, blew plastic water bottles apart and there was commentary of people with burned hands from it. I am working on this revolver and trying to make it safe to fire. So please tell me, am I being too particular? I have read in online forums about people complaining to Ruger or S&W that the gap on their new revolver is about .006" and others on the forum indicate that it should only be no more than .003" or something. I am talking here about a gap that is ten times that amount. So please give your opinion, does the gap really matter?
     
  21. Vern Humphrey

    Vern Humphrey Member

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    Ask the gun. Put in bearings and shoot it. If it shoots well, no need to go farther. If not, you need to set the barrel back a thread -- which will be expensive.
     
  22. 243winxb

    243winxb Member

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    Take the firearm to a qualified gunsmith for a check up.
     
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  23. mr.ridout

    mr.ridout Member

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    It is a top break gun. The barrel is cast into the fore frame. I imagine I will figure something out.
     
  24. RKRCPA

    RKRCPA Member

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    It sounds like material needs to be added to both ends of the cylinder. If you move the cylinder forward too far in an effort to close the barrel/cylinder gap you may very well create an excessive headspace condition.
     
  25. Zendude
    • Contributing Member

    Zendude Member

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    I could never find a gunsmith that would even touch an old top break revolver that I had. If the gun isn’t spitting debris back in your face when you fire it, and it is not having light strikes on the primers, then it may be more hassle than it’s worth to adjust it.
     
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