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Cylinder Indexing
- Thread starter borne2fly
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Seems like another solution in search of a problem ! If the dome clears the parallel stop side of the notch wall, being the widest part, what can the cut out contribute being mostly covered by the window anyway? I would think the more area one has on the stop side of the bolt head the better to check notch peen out.
I don't see any advantage only a weakening of the bolt head and less contact area to stop the cylinder rotation against the notch wall.
This is where the early bolt drop with a polished head pays dividends as it brakes the cylinder rotation inertia and lessons the contact pressure against the notch stop wall contact as the bolt head bottoms out in the notch. It contributes the same on the back side of the window and bolt contact area at rotation check .
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Well you're probably right for your particular application.
Many of my customers are cowboy shooters and run their guns rather fast and hard. Over the years my guns have proven to be for the most part "bullet proof" and if a problem showed up, a discussion was had with folks that knew what to do and that fix became a normal operation in my service.
So, as to your assumption of a weak bolt head, failure has never happened. The relief of the side of the bolt is to avoid the clearances in the bolt mounting screw pin, bolt head to bolt window as well as bolt head/notch clearances to allow contact with the tall edge of the notch.
An addition to the previous drawing may help clear things up.
The scale is exaggerated for easier understanding of the principle.
Mike
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Thank you for the details in your thinking as it helps to understand the reasoning progression in what is being shown. I enjoy the challenge to my own ideas and experience for improvement in both knowledge of techniques and a broader scope of what is being done in this area of gun craft.
Some aspects I believe to be improvement and others moot or degradation of sound revolver function.
None of this is aimed at your personality or character and would love to have you next door so we could swap ideas, argue and banter regularly.
Some aspects I believe to be improvement and others moot or degradation of sound revolver function.
None of this is aimed at your personality or character and would love to have you next door so we could swap ideas, argue and banter regularly.
The Remington bolt head has a greater angle along with a cylinder notch that typically has generous depth. I still clearance the tall side for notch protection but nothing on the top of the bolt.
As far as timing ( bolt drop) it should still contact the cylinder at least a bolt width before the notch . . . whether an approach is available or not.
Mike
Yessir. It doesn't matter if the approach is present or not. One bolt width (min.) BEFORE the locking notch. Colt, Remington and all makes of copies. The ROA and "3 screw" Rugers get 2 bolt widths because the bolt ( cyl latch) is thin.
Mike
I’ve noticed something about these open-frame Ubertis … when viewed from either side, the front face of the cylinder doesn’t appear parallel to the back face of the barrel assembly. Is that intentional? Were the original Colts this way?
At first, I thought this was an optical illusion or maybe the back face of the barrel assembly was machined at a slight angle to the barrel (however they are perfectly 90 degrees to each other). Seems that all this will tip the barrel upwards slightly, and the cylinder and barrel would not be perfectly in line.
So far I’ve used shims in the arbor to fix this, with a resulting increase in cylinder gap. But before I go much further I would like to make sure that I’m not working against a deliberate design feature.
At first, I thought this was an optical illusion or maybe the back face of the barrel assembly was machined at a slight angle to the barrel (however they are perfectly 90 degrees to each other). Seems that all this will tip the barrel upwards slightly, and the cylinder and barrel would not be perfectly in line.
So far I’ve used shims in the arbor to fix this, with a resulting increase in cylinder gap. But before I go much further I would like to make sure that I’m not working against a deliberate design feature.
Typically when setting up Uberti's ( or for that matter any open-top), the .0025" - .003" endshake ( probably even as much as .004", but I'm a " close tolerances" kinda guy!) has the barrel attitude pretty much right. I don't like an "obvious" up or down (by sight) alignment barrel attitude either. In any case, slight "correction" of the forcing cone area may be necessary. The most important aspect of arbor correction is the permanent consistency of the setup without "guesswork" of "wedge position" (which can move from shot to shot if too loose or as loosens!!) !
That gives you the ability to sight the revolver and maintain the sighting.
Mike
Why? It's really not necessary. Less than a degree up or down isn't going to make a hill of beans ( that can be addressed with bullet weight). I've not had ( or felt the need to) do that in over 10 yrs.! (It's It's busy work for the bored or a really good Bubba correction!! Lol)
BTW, .0025" - .003" is much more efficient and cleaner than .004".
Mike
I reckon I just have a thing about the aesthetics. And it gives the machine tools something to do
-Don
I understand the "idea of" but that joint is a butt joint and receives it's seating from the wedge as well ( it should have contact before the wedge is driven in). So, if you go too far with your "clearancing" and the frame / barrel lug is just "kissing" when assembled, it won't be a solid support when firing. (the lug will hammer the frame under recoil).
That joint is the foundation of the setup and the arbor is the "adjustable" / fine tuning aspect of the setup and the endshake "dialed in" is the result.
If your going to worry about those things, just take a look at how well centered the bore is in the barrel itself. Sometimes they're close, most of the time either end will surprise you with how "off axis" it actually is.
Just trying to help.
Mike
>> “most of the time either end will surprise you with how "off axis" it actually is.”
Yes indeed. I’ve seen that when I spin the barrels in the lathe. It’s a little unnerving. When I bore a hole it’s always properly centered in the work, so things like that make me question the rest of the machine work throughout the entire gun. Granted, it’s supposedly all CNC these days, but CNC is only as good as the programmer.
I understand what you’re saying about the arbor being the adjustment. I’ll be careful to leave some meat on the lug so as to preserve the adjustability you’ve mentioned.
Thanks again for all your advice. I enjoy learning about all this.
-Don
I finally got around to making a range rod and ran it down the barrel. Also made hollow brass slugs for each of the cylinders. The range rod fits the barrel perfectly, and steps down to the ID of the brass slugs for the last 0.25” or so. The rod feeds through the barrel and seats into the slugs without hanging up anywhere. Excellent.
I did notice a small change in ID with the cylinder chambers about halfway down each chamber. Had to make a corresponding step in the brass slugs for a good fit. Not sure why that’s made that way. I’ve seen that with other revolvers as well.
My spare Uberti cylinders don’t fit this gun. The cylinder chambers sit on a slightly different radius from the center of the cylinder. It’s enough to stop the range rod. Maybe Pietta cylinders might fit, but I suspect this gun is a bit of an oddball and any spare cylinders would have to be something I make.
I have a few newer Uberti revolvers and I was relieved to find that they all pass this range rod alignment test even when I change cylinders. I think we can credit modern CNC machining for that.
I did notice a small change in ID with the cylinder chambers about halfway down each chamber. Had to make a corresponding step in the brass slugs for a good fit. Not sure why that’s made that way. I’ve seen that with other revolvers as well.
My spare Uberti cylinders don’t fit this gun. The cylinder chambers sit on a slightly different radius from the center of the cylinder. It’s enough to stop the range rod. Maybe Pietta cylinders might fit, but I suspect this gun is a bit of an oddball and any spare cylinders would have to be something I make.
I have a few newer Uberti revolvers and I was relieved to find that they all pass this range rod alignment test even when I change cylinders. I think we can credit modern CNC machining for that.
