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wedge problems on pietta colt army

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Mean Gene

40 Cal.
Joined
May 16, 2016
Messages
432
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Location
People's Republic Calif
Hi guys, I'm having problems again with my wedge backing out of the slot with every shot.
This has been an ongoing problem for this particular gun, I keep tapping it in and it keeps backing out.
I was thinking of putting an arch in the shape of the wedge so as to maybe put down ward pressure while in the slot.
Any suggestions as always would be greatly appreciated.
 
IF it's a bad wedge I'd mail DGW $10.95 for a new one. If it's an oversized slot you may need more drastic repairs...without pics and measurements it's hard to say.
 
I had the same problem with one of my Pietta revolvers. I tried bending the wedge spring up which helped but the problem seemed to resolve itself the more I shot the gun.

Don
 
Sounds like the wedge is too small. One side of the wedge is straight the other edge is tapered. It only needs thumb pressure, if it is the right size. It should go in just past where the lip of the spring passes thru the far side of the frame. If it goes in all the way, to where the lip bumps the screw, then it is undersize.
 
My guess is the mandrel is not bottoming out when the wedge is fully inserted which means it looses it's leverage against an anchor leaving only slot friction to keep it in place.
Often when this happens the barrel will pitch up ward and cylinder gap will be tight at the top and loose on the bottom.
The bottom out in the mandrel well should equal the pitch up from the lower lug drawing the barrel breech face back parallel to the cylinder face.
Actually this can be used to gain some elevation adjustment but the best method is to make the cylinder gap even all the way around and adjust elevation with sight manipulation.
 
I will check for that, I just wrecked a brand new wedge while shooting it.
I have two that are S shaped from damage done just shooting it the newest one looks like it was beat up pretty bad. If the mandrel isn't bottoming out, what would you think would work to fix the problem?
 
I will check for that, I just wrecked a brand new wedge while shooting it.
I have two that are S shaped from damage done just shooting it the newest one looks like it was beat up pretty bad. If the mandrel isn't bottoming out, what would you think would work to fix the problem?
 
You can drill and tap a set screw in the end or make a steel plug to drop down the well. The set screw can weaken the slot so I like the plug method.
 
A short arbor is generally a Uberti problem but it is simple enough to check. Just remove the barrel and cylinder then put the barrel back on rotated 30or so degrees till the arbor bottoms out then try to rotate it into position if it just clears the frame you don't have a problem there if not you can shim it out , like M.D. said, with a washer of the correct thickness down the arbor hole in the barrel.
More likely though your problem is the wedge is too small and is allowing the barrel to act like a projectile when fired. Easy to check just put the wedge in and if it touches the screw head it is too small. If so you can make a new larger wedge which is not hard by machine but somewhat tedious by hand. Or the simple solution is solder about a .010 shim to the back of the wedge. The side that faces the cylinder. You may have to fit it a bit just make sure to remove material evenly.
 
I use a screw head, in my Dragoon. I hack sawed the head off of a screw, and place it with the rounded part down. It lays in there perfectly. I got them to send me a new wedge, but the one they sent was even smaller, so I made a new one.

I can't figure out why they can't get it right, when the gun is built. One would think, with today's technology and cnc machining, they could produce better fitting parts.
 
The wedge problem with Uberti Dragoons seems to be universal. I've owned several and worked on others and every one had a wedge that was too small. Not so with other Uberti's like the Navy and Army.
 
I like to use a magic marker to color both sides of the wedge to see what is making contact inside the slot.
Ideally it should contact only the mandrel/arbor slot at the muzzle side and both sides of the barrel slot on the cylinder side.
This spotting method is how I fit the new wedge.
I like to radius the entry side corner of the arbor slot a bit and both end corners of the wedge to aid insertion. Also check the wedge for edge peen over which means it's to soft.
I make my own out of A-2 tool steel and once hardened they never batter.
O-1 tool steel works fine as well but A-2 is less likely to warp when air quenched.
 
All good things to know M.D. of course you know I think the tool steel is overkill. I still think from Gene's description that the wedge is fully inserted and not making contact with the front of the arbor slot. Only explanation I can think of for the amount of distortion he is reporting.Hopefully there has been no damage to the rear of the slot in the barrel.
 
I have usually had to give all three slots ( arbor and barrel) some file strokes to get them all to even load the wedge, thus the reason for spotting them in with magic marker which does not scuff off nearly as easy as if using a liquid spotter. It won't scuff off until it is loaded with some pressure.
The tool steel wedges work very well because they never deform at all making it easy to spot fit the wedge to the slots which are all softer.
 
Hello everyone, I checked to see if the arbor was reaching the bottom.
With the cylinder installed on the arbor and rotating the barrel 90°. With the barrel rotated it dropped down to the cylinder face 1mm.
with out the cylinder on the arbor the barrel slid down 2 mm before bottoming out.
Will study all the suggestions and see which I can make work.
Thanks again everyone, all good suggestions and I really do appreciate your thoughts.
 
If you get that plug in the arbor well so the arbor can bottom out even to the lower lug pitch up, I think you will solve your wedge loosening trouble.
If your going to make a wedge then the angle goes on the muzzle side. If you think about it you will see why as the arbor has a single slot and the barrel has two.
 
MD, if I were looking for tool steel where would be a good place to start, should I maybe buy a chisel and grind it down to size, or can I find it at a hardware store?
I've never actually went out looking to buy tool steel.
 
Gene I think you may have missed the point there. When checking for arbor bottoming out it has nothing to do with the cylinder. Do the check with the cylinder off the arbor and install the barrel rotated 90 degrees. Bottom out the arbor then try to rotate the barrel into position it should ,if everything is right just clear the frame shelf where the locater pins are at. If it does not then the arbor is to short and you need a plug. The idea is that the arbor bottom out at the same time the barrel lug meets the frame. That allows the wedge to lock them solidly together.
If you are going to make a new wedge then you need to know that the taper on the wedge needs to be precise. There is a taper in the end of the arbor that mates with the wedge to lock the two together.
 

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