Open Top Question

[Catdad]

I have an Uberti 1872 Navy Open Top and am having problems with it.  First time I took it out shooting, it would occassionally not fire and the problem got worse as I went along.  So I took it back to the dealer and he found some burrs in it which were causing the misfires.  Problem solved?  Not quite.  I took it out a second time and tried to put a box of 50 through it.  It did shoot a lot better (not as many misses), but wasn't quite there.  Okay, I thought, maybe I'm doing something wrong so I asked him about it.  He did tell me after loading it, I'd have to cock the hammer all the way back, then release it, then cock back and fire.  It is plausable the second time shooting, I didn't always do that.  Third time out, I got nothing but misfires, so once again, I asked my dealer. He said, he's experienced the same type of problem with Open Tops before when the wedge wasn't in quite the right position. He said, he's seen four recently that if the position of the wedge was off by as little as 1/16th inch, the gun wouldn't fire. I've been reading this forum a couple of weeks now and haven't seen that addressed.  Will the positioning of the wedge really affect the firing (or not firing).  I know I don't have pushed in too far, because there is no problem with the cylinder turning.

[Fox Creek Kid]

Let's cut to the chase: are these light hits on the primers with small indentations? If so, then your firing pin length/headspace is wrong. It should never have left the factory like that but it happens. Option #1:  send it back to the importer, i.e. Cimarron, Taylor's, etc. Option #2:  call VTI gun parts and order two new firing pins and have a COMPETENT CAS gunsmith install & regulate.

[Major 2]

yes the wedge placement is important... same with the C&B's

I would only add to Fox Creek Kids assessment....

Firing pins from The Smith Shop ....  http://www.thesmithshop.com/

I think he could cure the common cold

[Flint]

The proper position for the Opentop wedge is with the inside face of the screw clearance groove against the screw head.   Push the wedge in until the screw will turn past its flat on the head, then turn the screw on in to the barrel.  Now back the wedge until it is against the screw head (careful not to break the screw head).  If it won't go that far it's too tight, if it goes way past that point it's too loose.

If the wedge is driven too far the gas ring on the front of the cylinder will clamp and the cylinder won't turn.  The cylinder gap is set by the gas ring as well as the headspace.

I never had a problem firing, but did have pierced primers, and had to shorten the hammer nose, which was too long and too sharp.  Check to determiune if your misfires are possibly caused by cylinder overtravel, a common Opentop problem, causing many shooters to consider the gun a duelist (one hand) only gun.  Two handed shooting spins the cylinder too fast.

With a strong enough hand spring it will not overtravel.  I converted mine to use a Ruger coil and plunger which solved the problem.  Check to see whether your firing pin strikes are centered.  If you see dimples off center on the primer or elsewhere beside the primer on the head of the cartridge case, you have overtravel, and a misfire.

[Goody]

"I converted mine to use a Ruger coil and plunger which solved the problem."

Flint, can you elucidate this process, do you have any pictures?

thanks

[Flint]

I will, later today.

[Catdad]

Check to determiune if your misfires are possibly caused by cylinder overtravel, a common Opentop problem, causing many shooters to consider the gun a duelist (one hand) only gun.  Two handed shooting spins the cylinder too fast.

With a strong enough hand spring it will not overtravel.  I converted mine to use a Ruger coil and plunger which solved the problem.  Check to see whether your firing pin strikes are centered.  If you see dimples off center on the primer or elsewhere beside the primer on the head of the cartridge case, you have overtravel, and a misfire.

Thanks for the advice on wedge placement, Flint. I don't understand what you mean by cylinder overtravel or how two handed shooting would spin the cylinder too fast.

After reading the replies to my problem (thanks to all who advised!!!), I wouldn't be a bit surprised to find out that the problem is a combination of firing pin and wedge placement.  Stay tuned for further developments (once I find out for sure).

[Flint]

Most two hand shooters cock with the supporting hand's thumb.  The hammer can be cocked much faster and harder with the off hand thumb than with the shooting hand thumb, and can overrun the springs inside, allowing the cylinder to skip past the bolt notch.  For some reason I can't figure out, the Opentop is more prone to this than the SAA or the cap & ball guns.

Logic would say the problem is the bolt spring being too weak (which can be the probem) but more often it is the hand spring.  Apparently the hand rubbing against the cylinder rachet acts like a brake, slowing the spin.  A weak hand spring can cause cylinder overtravel, and often does.

As I mentioned, one sure way of checking if it is misfiring is to look for firing pin strikes in the case head or way off center on the primer.

I will disassemble and photograph a Ruger coil and plunger installation in a Colt type clone tomorrow.  It can also be done on a Remington, but the spring retaining screw will show on the outside as it does on the Ruger Bearcat.

[Flint]

Finally took photos of the Ruger coil and plunger mod to the Opentop.

First drill hole, min 7/64, max #33 (.113) halfway between the backstrap screw hole and the top of the left frame boss, .100 inch from left edge of hammer slot, thru to hand channel..



The leaf spring is completely removed, burrs smoothed, rear face of hand is smoothed and/or polished.  notice the stripe where the Ruger plunger has rubbed.



Therse are the parts, and I added a #6-32 X 1/8 set screw.  Tap the start of the hole in the frame only deep enough to accept the screw flush.



The spring and plunger in place before the set screw is installed.  Insert the spring and plunger only after the hammer and hand are reinstalled.  If disassembling the gun, remove the spring and plunger before removing the hammer and hand from the frame.



Note the set screw in place, and flush.  This adds a bit more tension, and keeps the spring in place when removing the backstrap.  The set screw is optional depending on the spring tension and the ease of assy and disassy. desired.

[Mako]

Flint,
EXCELLENT!!! pictures and explanation... 

Thank you for the effort.
Mako

[Coffinmaker]

Flint's added post for the spring and plunger hand spring is too good to lose. BTT

Coffiinmaker

[Coffinmaker]

Coming back around ........again.

Interestingly, the last three "new built" Open Tops to come into the shop for a little "TLC" were drilled and tapped at the factory.  Go figure.


Coffinmaker