'51 Opentop problems

[Montana Slim]

Cylinder to barrel gap on 2 each Uberti 1860 & Pietta 1860 Colts (Percussion) that I most frequently use run no more than .004".
And I assure you they function quite well even using Elephant BP.

A larger gap doesn't hurt on some revolvers, depending on their particular design features.

Regards,
Slim

[5judge]

OK. Dropped the newly acquired washer in the open top and reassembled. Shall report back when I can next range it. Right now ten inches of fresh snow's keeping me home, happily casting .358" bullets and watching "Last Stand at Saber River" on DVD in my basement work room.

[Mako]

5judge,
Do you have any feeler gages?  I'm talking about flat gages that you may have used to set spark plug gaps or points on your cars in the past.  If you do I'm curious as to what your cylinder gap is right now.

If you don't have gages, use paper.  Use notebook paper, don't measure with a folded edge (it will be thicker).  One sheet will run about .0030 -.00325"; so you want two sheets to fit for your cylinder gap.  That will give you a gap of .006 to around .009".  If three fit you are over .009".

When you measure have the pistol un-cocked and put slight rearward pressure on the cylinder to make sure you are measuring your maximum gap.

To make sure the washer is actually doing something think back to when you when you replaced the barrel after adding the washer, did it hold it off of the face before you put the wedge back in? You have a 99 left, so you might want to try it again with a fresh washer and observe what happens.

An even better idea would be to remove the washer, reassemble the pistol and then measure your gap.  Then add a fresh washer and try it again.  The only reason I am suggesting a fresh washer is that it will take a slight set the first time you install it.  I want you to feel the interference (to make sure it is there) the first time it is compressed.  Now remeasure your gap.

Hopefully it went from zero or one sheet of paper to now accepting two sheets of paper.  Or if you have feeler gages; from .003" or less to .006-.008".  If it accepts three sheets or is greater than .009" with a feeler gage you need to back off on the amount your wedge is pressed in.

Since you have a Uberti Richards-Mason the wedge has that slot and the screw that has the flat cut on it.  I know some people don't like the idea, but you can use that slot and the screw to set your length. I like to use the minimum engagement that will retain the wedge on any new set-up of a pistol.  This gives you additional tightening capability if the pistol wears over the years.  If you bottom it out the first time you will have no additional adjustment over time.

Since you are using a spring (the washer) and not a true hard stop at this point, you can "over-tighten" the wedge and close the gap.  The washer gives resistance and makes it much easier to set the gap. Try this simple procedure to set your gap:

• After replacing the barrel tap your wedge in until you see the clearance slot on the wedge just pass the edge of the barrel.
• Turn the screw down, the edge should now be blocking the wedge.
• Tap the wedge back very lightly to just touch the screw.  (this is the minimum engagement possible with your screw fully tightened)
• Check your gap.  If it is less than two sheets of paper or .006" then you will need to move the wedge out.  If it accepts three sheets or is more than .009" then we need to move it in deeper.
• Moving it out a controlled distance is the easiest change at this point.  You back the wedge screw out a complete revolution, the screw's pitch is .028 per inch so the screw will move out that much.  Now tap your wedge back to the screw and remeasure.
• Remeasure, and it should be at least .001" greater than it was before.  The wedge taper is only about 2°15' overall.  So you can turn your screw out however many full revolutions you need (at a gain of .001" per turn) to get your gap of .006-.008".
• Going smaller is tougher to gauge because you lose your screw as a reference point.  The good news is that this shouldn't be a problem for you because by all indications your gap started too tight.

If you find a washer that literally fills the gap in the arbor to arbor hole relationship the gap is preset each time you reassemble.  A purpose built spacer is even better, that is the ultimate solution.  Did you read Pettifogger's articles in the links I posted for you?  Once this is set, the gap can't change as long as you have some wedging action.  You want to slightly "spring" the barrel lug every time the barrel is reassembled.  I have an original 1860 built in 1861 and it still does this.  The creep of steel (even wimpy 1860's time period steel) is low and it has held up for 149 years.  As long as you don't drive the wedge in with a 5 pound hammer the steel acting as a spring should keep you out of trouble.

I shoot loose powder 1860's almost exclusively in matches and I reload off of the pistol, which means I disassemble them every 5 shots.  I have mine set so that I tap the wedges in until the spring lip (you don't have one on your Uberti cartridge pistol wedge) just clears the barrel on the other side. I do this to aid in dis-assembly in the next few minutes.  It also serves as a visual indicator I have reassembled the pistol correctly.  With this insertion a few taps with a wooden dowel disassembles the pistol.  I have not experienced any measurable wear over the years of doing this with constant dis-assembly.

Regards,
Mako

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[Rebel Dave]

Mako, FCK, Raven, and all

Thanks for some good info on open tops, and C&Bs. I am now working on my 4 open tops, including my 2 45s, after that come my C&Bs. Lots of good info in this thread. Thanks guys.

Rebel Dave       aka      Dave C.

[StrawHat]

Marking for reference