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Pietta 1851's bolt is "unbolting"

Discussion in 'Blackpowder' started by ClemBert, Apr 14, 2010.

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  1. ClemBert

    ClemBert Member

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    I have a fairly new Pietta 1851 that probably only has about 50 rounds through it. I've noticed just recently, while fondling it, that the bolt is "unbolting" after the hammer falls.

    Step 1. Cock the hammer all the way back.

    Step 2. Check to make sure the cylinder in locked in place by the bolt by attempting to rotate it both directions.

    Step 3. Pull the trigger.

    Step 4. Observe that the bolt has unbolted and allowed the cylinder to rotate an additional 0.060" to 0.080".

    I've checked the width of the bolt and the width of the cylinder slots to make sure that the bolt width is less than the cylinder slots. The hammer is hitting the nipples and this is causing the problem. I verified this by removing the nipples then dry firing without them. The problem is clearly related to the hammer hitting the nipples. I'm just a bit surprised that the force of the hammer just barely hitting the nipples is causing the bolt to unbolt. Looks like it is time to take a file to the nipples.

    Anyone ever experience this problem?
     
  2. BCRider

    BCRider Member

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    I doubt that you want to take a file to the nipples. They require the sharp tapered edge to seat against the primer and generate the small contact point of pressure needed to set the primer's off.

    Also your "bolt" is typically referred to as the cylinder stop.

    Under the trigger guard there's a spring that acts as the trigger return for one side and the cylinder stop tension on the other. If that spring is not adjusted correctly or has broken so that there's little or no tension on the stop it would allow the shock of the hammer striking the cylinder to jar the stop out of the cylinder notch. You can test this without taking the gun apart. Remove the barrel and cylinder so you can see and feel tension in the stop. Going to half cock should retract the stop. Going to full cock should bring the stop back up and leave it sticking up with a goodly amount of spring tension in it when you push on it. If you can easily push it down then the spring is either partly broken or if you were in there at some point it may be in upside down or something odd such as that.

    Also you should pad the nipples with a popsicle stick, bit of storage container plastic or similar while dry firing. The nipples are hard and they will leave a ring shaped dent in the hammer which is only case hardened. At least that's what happened to my own Euroarms 1851 prior to me getting it from the last owner.
     
  3. ClemBert

    ClemBert Member

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    Was just using the terminology that VTI Gun Parts and Larson E. Pettifogger uses.

    The trigger bolt spring seems fine. I only took it out for the first time today when I noticed the problem.

    The bolt mechanism seems to be working just fine. Also, there is normal tension on it. With the cylinder off and the hammer cocked the bolt can be pushed down with similar effort to my other BP revolvers.
     
    Last edited: Apr 14, 2010
  4. Bluehawk

    Bluehawk Member

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    Whats with the ridiculous prices at VTI?? Their Pietta 1858 Remington Common Parts set is $55.00...Cabelas sells it for $30...(most of those parts fit the Spiller&Burr)...they want $85 for the cylinder...Cabelas sells that for $40!!!!
     
  5. Tomahawk674

    Tomahawk674 Member

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    I didn't know you could buy parts at Cabela's....
     
  6. BCRider

    BCRider Member

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    Well I'm stumped. That was the only thing I could imagine would cause it to unbolt.
     
  7. ClemBert

    ClemBert Member

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    Maybe the trigger bolt spring just needs to be stronger. Just seems strange that even though there seems to be sufficient tension that the bolt is bouncing enough to let loose and the cylinder is advancing about 0.080". The cylinder rotates just a bit but then the hammer ends up on the left side of the nipple slot. It is the nipple slot hammer relationship that prevents the cylinder from rotating even more. It has the effect of wacking the left side of the nipple slot and marring that edge of of the cylinder's nipple slot.

    Additionally, while it may not be great that the hammer hits the nipple I imagine that even if I shorten the nipples that with a cap in place the hammer is still going to transfer some of the energy to the cylinder because the hammer must hit the cap and the cap must hit the nipple.
     
  8. mykeal

    mykeal Member

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    Hmmm. I've typically referred to it as a 'bolt' for about 35 years. Guess I'll have to learn it all over again.
     
  9. Fingers McGee

    Fingers McGee Member

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    Dress the face of the hammer so it doesn't hit the nipples. Should solve the problem. I've had to do it to a few of my C&Bs so they would function correctly. One was so bad, the action would lock completely up. Hammer wouldn't go forward enough to catch the legs of the bolt. A little dremel/file work to the hammer face fixed it right up.

    FM
     
  10. madcratebuilder

    madcratebuilder Member

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    You have been working on to many S&W revolvers Rider. Several names for the same part.

    Colt and Remington use the term "Bolt"
    S&W uses "Cylinder stop"
    Ruger uses "Cylinder latch"


    From your description I would say you have a weak bolt spring or to much tension on the bolt leg. As the hammer falls the bolt leg has to ride over the cam button and bolt spring tension should keep the bolt in place and the bolt leg should flex in as it rides over the cam. On your revolver it sounds like the leg tension is overcoming the bolt spring tension. Look for burrs on the bolt leg and the cam button, lubricate that area and see what happens.

    [​IMG]
     
  11. TheRodDoc

    TheRodDoc Member

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    For the 1851 it could also be to large of cylinder gap or ill fitted bolt to cylinder notch fore and aft.

    If the bolt is back to far in the cylinder notch the bolt won't seat deep enough. When your hammer is hitting the nipples (which it shouldn't) it will push the cylinder ahead. It the cylinder gap is too large, (Should be 2 to 3 thousandths for the 1851 colt) the cylinder moves ahead which bounces the bolt completly out of cylinder notch.
    If cylinder gap is excessive that can happen even if the bolt was fitted perfect when cylinder is at the back. If the hammer sitting on the nipple turns the cylinder even slightly then the bolt won't bounce back into the notch.
    View attachment 119610
     
    Last edited: Aug 27, 2011
  12. ClemBert

    ClemBert Member

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    I filed the bolt leg just slightly to make sure there is a smooth transition as it rides the cam button. I polished the cam button and the bolt leg. I put lube over all contact points. Last, I very gently bent the bolt spring slightly more so more tension is applied to the bolt.

    Unfortunately, none of these steps helped. Again, with the nipples removed from the cylinder everything operates just fine. With the nipples in place and the hammer hitting the nipples this phenomenon is observed. It doesn't happen everytime but perhaps one to three times on every cylinder revolution. This problem didn't exist originally, or perhaps I wasn't observant in the beginning.
     
    Last edited: Apr 15, 2010
  13. ClemBert

    ClemBert Member

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    I don't have much cylinder gap. The gap is rather small and you'd have to hold the revolver up to the light and look carefully to see the gap.

    You could be onto something here. However, I already checked all the cylinder slots and the width of the bolt. In fact I filed on the bolt just a little to make sure it fits in the cylinder slots. Previously, it was questionable if the bolt was dropping all the way into the slots.

    I know they say "Italian black powder replicas make gunsmiths of all of us" but this is starting to annoy me. :cuss: I'd rather be shooting. Maybe I ought to spend more time with my Uberti 1858 and Uberti Walker to get the grin back on my face.
     
  14. BCRider

    BCRider Member

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    Very much guilty as charged.... :D I have to admit that this is the very first info I've seen where someone called these the cylinder bolt. I humbly accept this newfound knowledge and bow low in respect to the accumulated knowledge base of all here and to aid in dislodging the egg on my face.... :D

    So the proper way is that the hammer should be able to dry fire and not strike the nipples? I'm loathe to file or grind off the face of the hammer to achieve this and remove the case hardening. Is trimming the ends of the nipples an option as long as they don't get too short? Or am I worrying about nothing and it's kosher to have at the hammer face? What about adding a bumper pad at some point in the frame so that it holds the hammer back slightly off the nipples?
     
  15. Bluehawk

    Bluehawk Member

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    Wow, that is a tiny gap...I just posted yesterday the barrel/cylinder gap on my Spiller & Burr is .007"...is my revolver in trouble??
     
  16. mykeal

    mykeal Member

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    In a perfectly timed bp revolver the hammer will strike the frame just short of the hammer face hitting the nipple cone. The hammer face will, however, be close enough to drive the cap onto the nipple hard enough to set off the pyrotechnic material in the cap. If there is no cap in position the hammer face will not contact the nipple cone (remember, this is in a perfectly timed revolver) so that it is possible to dry fire the gun without damaging the nipples.

    This perfection is rarely achieved in practice, however. One would need the assembly of nipples and cylinder to provide 6 firing positions that do not vary within thousandths of an inch despite cylinder end play and many other factors. It can be done, however, with careful attention to detail and good working knowledge of how the single action revolver works.
     
  17. TheRodDoc

    TheRodDoc Member

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    And to add to what mykeal said, This is one of the reasons for a close cylinder gap. If the cylinder is allowed to move forward more then a couple thousandths the hammer can't hold the seal on the cap after it ignites for the hammer is sitting on the back frame. With a bigger gap then 3 thousandths the cylinder will move ahead to much and let the cap loose under the hammer. And the preasure will blow the cap open or blow pieces of it into the action. My 1851 colt has only .001 for the cylinder gap. The gun always works flawlessly. I never use grease in it though. That will just gum up the works.

    The second reason for a tight cylinder gap is to lessen the fouling problem. The tighter it is the less leakage there is and the less preasure there is to blow powder residue into the arbor.
     
  18. Bluehawk

    Bluehawk Member

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    That's interesting...I think my Spiller & Burr has a boss on the front of the cylinder where the pin goes through so I'm assuming that holds it firmly in place against the frame to keep it from having excess cylinder end play. (My new Remington doesn't have that.) Sound correct?
    On another thread it was mentioned .008" was considered optimum for barrel/cylinder gap for a Colt BP revolver, so now I'm confused! :banghead:
     
  19. Bluehawk

    Bluehawk Member

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    Is that a typo? Standard notebook paper is .002" thick! We are talking about barrel to cylinder gap...correct?
     
  20. BCRider

    BCRider Member

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    Hmmm.... something tells me there's a lot of good stuff to be learned here as we help solve this unbolting issue.

    Gotta go have a closer look with feeler guages at my own 1851.
     
  21. ClemBert

    ClemBert Member

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    I broke out my feeler gauges. With the hammer in half cock and full cock and pushing the cylinder towards the hammer with much thumb pressure I measure a gap of 0.002".

    I took the clockworks out again and remeasured the bolt width and the cylinder slots. I don't have a clue as to what to look for now. I even polished both sides of the bolt. Still having the problem. I'm stumped. :cuss:

    Maybe I should just order the bolt/hammer/trigger (common parts) kit and swap the parts out. This Pietta is darn near new. Only about 50 rounds through it. So far I'm very underwhelmed with Pietta quality. Its a shame that I probably won't learn my lesson and will probably order some of those Piettas on sale at Cabelas. Guess I'm a masochist.
     
  22. mykeal

    mykeal Member

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    I don't understand that. When the cap ignites it sets off the main charge and the cylinder moves backwards, not forwards. It's called recoil. The cap is blown off by back pressure from the main charge when the mainspring is too weak, not because the cylinder moves forward when the cap goes off.

    Pressure depends on the rate of burn, not how big the chamber is. The units of pressure are pounds per square inch, and it is uniform throughout the vessel. The amount of pressure blowing combustion byproducts out of the cylinder gap is the same regardless of how big the gap is.

    A 0.001" cylinder gap is too small. I think you've misplaced a decimal point.
     
  23. TheRodDoc

    TheRodDoc Member

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    I guess you will just have to try it as far as the gap leaking less the tighter it is. I do use one thousandths gap for my colts. It's not too tight.

    Most will know that if you poke a hole in your car tire with a small nail it will leak at a certian amount in lets say one second.

    Now poke it with a big knife and see that it leaked much more in that second.
     
  24. madcratebuilder

    madcratebuilder Member

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    I respectfully disagree. Colt specified .008 for it's cap and ball revolvers. The gunsmithing manuals I have that cover cap and ball call for .006-.010.

    A gap of .002-.003 is going to cause cylinder drag after the first cylinder is fired. The .002-.003 would be tight for centerfire smokeless revolvers. S&W calls for .004-.006 on K and N frames, DW is .006-.008 for it's big bore magnums with the exception of the .357 supermag , that's .002 only to reduce top strap erosion.
     
  25. ClemBert

    ClemBert Member

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    I'm expecting my 0.002 gap in increase a tad as I break in this revolver. However, with only 50 rounds through it I'm unlikely to break it in if I don't resolve this issue. I'm kind of surprise that no one else has reported seeing this problem.
     
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