Do Colts Open Tops Shift POI?

I had two previous sessions with the 47 Walker and my home built front sight. The unmentionable cylinder was hitting 5 inches high, BP cylinder quite close at a tad low.

Today, the unemotional loads were hitting pretty close to POA, got some decent groups.

So the $64 question is, can that shift if the barrel seats differently in regards to key and arbor?

Smokerr said:

I had two previous sessions with the 47 Walker and my home built front sight. The unmentionable cylinder was hitting 5 inches high, BP cylinder quite close at a tad low.

Today, the unemotional loads were hitting pretty close to POA, got some decent groups.

So the $64 question is, can that shift if the barrel seats differently in regards to key and arbor?

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Yes. If the arbor is too short you will get a bunch of variation in vertical spread. Every time you seat the wedge it'l be a bit different, and if it's bad enough, it'l move around as you shoot.

When the arbor is short, if you drive the wedge in further, it'l raise the point of impact. Only good way to avoid this is to correct the arbor length.

I do have it shimmed. Oddly it was consistent high with unmentionable and not shifting around cylinder change to cylinder change. . I am trying to be consistent with the smack to seat the wedge

Other thought was sight picture but not sure why I would change it as I know to fill the notch with the sight and even on the top. Vs why would I shift even not intentionally with the BP cylinder.

A bit baffled but the groups were better today as well.

Smokerr said:

I do have it shimmed. Oddly it was consistent high with unmentionable and not shifting around cylinder change to cylinder change. . I am trying to be consistent with the smack to seat the wedge

Other thought was sight picture but not sure why I would change it as I know to fill the notch with the sight and even on the top. Vs why would I shift even not intentionally with the BP cylinder.

A bit baffled but the groups were better today as well.

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Is the arbor length exact? If it is, it shouldn't matter how hard you drive the wedge in, unless you're doing it hard enough to actually smash and shift metal.

Sometimes it seems bullets go where they want, but usually it is us. Any small thing, trigger pull, lighting on the sight picture, a little more or less shaky, etc. Even shooting off the bench can have human factors involved.

It's inherent in the design and the main reason you will almost never see them in MLAIC matches.

Uncle Miltie said:

It's inherent in the design and the main reason you will almost never see them in MLAIC matches.

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It's inherent in the Uberti execution of a most excellent design!!
If the arbor length is correct, the sight line will be the same every single time.
Smokerr, if you have a CORRECT spacer that's actually thick enough, the poi will be the same every time. A HARD tap isn't the same as screwdriver handel tap. If the wedge isn't driven in, it can vibrate around and allow changes from shot to shot. If a hard tap locks the cylinder up, the spacer is obviously not thick enough.
It's a lot easier to start with a "too thick" spacer and thin it down to what you want your endshake to be. Shimming UP to get your endshake isn't a good way to achieve the same thing.

Edit: otherwise, you couldn't shoot five shot groups like this (shot in blue circle was from a different grouping/ different revolver).


Mike

I bought a plastic mallet I keep in my BP box so when at the range I have at least a consistent device to tap, or course how hard I tap it varies but I try to keep it the same.

I had over shimmed it and was getting a lock up. I might be able to add some super thing shim material and get a tad tighter, but I have something around .002-.003 with both cylinders. Even pull top and bottom so the geometry seems to be square.

I noted last night when doing my gap checks that the Wedge is moving a bit deeper into the slot with the tap now.

I am guessing my shims are compressing. Still good and I have a bit of space before it hits the screw.

Add a small thickness shim if it does hit the Screw on the shim?

Smokerr said:

I noted last night when doing my gap checks that the Wedge is moving a bit deeper into the slot with the tap now.

I am guessing my shims are compressing. Still good and I have a bit of space before it hits the screw.

Add a small thickness shim if it does hit the Screw on the shim?

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What do your shims look like? I try to avoid multiple pieces, but if I mess up, or am too lazy to fit something for the 15th time, It's nice to have a set of shims on hand. Bought a big assortment from triggershims.com a while back to fix an 1858 hammer issue, and they've been really helpful.

If you do something like this, you won't have a problem with stuff compressing.



A machine screw would have been easier, but I didn't have one on hand with a wide enough head. If your leading shim doesn't have a bevel on the front, the edges can compress. Better to have a larger beveled bearing surface, then you can just swap out thin shims until you get things perfect.

One Shim is a washer up in the Arbor hole and the other is a beer can cut out.

Smokerr said:

I noted last night when doing my gap checks that the Wedge is moving a bit deeper into the slot with the tap now.

I am guessing my shims are compressing. Still good and I have a bit of space before it hits the screw.

Add a small thickness shim if it does hit the Screw on the shim?

Click to expand...

Smokerr, I think you would be better served with a single spacer. I started off with shims but that proved to be inadequate in Walkers when heavy charges and or heavy bullets were used. The single steel or stainless spacer proved to be the right setup and that's what I've used for ten years now. With the loads I shoot in my Dragoons now, it's even more evident that it's the right setup. No sense in going to a "lesser" setup when the "best" setup is so easy to do!!

Mike

45D said:

Smokerr, I think you would be better served with a single spacer. I started off with shims but that proved to be inadequate in Walkers when heavy charges and or heavy bullets were used. The single steel or stainless spacer proved to be the right setup and that's what I've used for ten years now. With the loads I shoot in my Dragoons now, it's even more evident that it's the right setup. No sense in going to a "lesser" setup when the "best" setup is so easy to do!!

Mike

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Mike:
Thank you. I am a bit lazy in once I got it working I tend to leave it. I will keep an eye on it. There is one large spacer and the beer can. Shim is probably not the right term though the beer can might be a shim.
I would have to dig the setup out and I glued the bottom one in.
Am I right in thinking that if the wedge is going in further its compressing more? The gap measurements seem to indicate that. I get the idea of how it works but have not been able to internalize it where I have a good mental model. Maybe Animigrphics will do one on that!

The yellow painted pencil is your friend.
When you're reducing the thickness of a washer (spacer) use the eraser end to hold the washer down while grinding it against the stone.

Anyone else getting lots of format options and weird stuff with reading some of the Posts?

Smokerr said:

Mike:
Thank you. I am a bit lazy in once I got it working I tend to leave it. I will keep an eye on it. There is one large spacer and the beer can. Shim is probably not the right term though the beer can might be a shim.
I would have to dig the setup out and I glued the bottom one in.
Am I right in thinking that if the wedge is going in further its compressing more? The gap measurements seem to indicate that. I get the idea of how it works but have not been able to internalize it where I have a good mental model. Maybe Animigrphics will do one on that!

Click to expand...

Yes. If the wedge goes in further and you have a "shim stack", it's probably the shims compressing or any film of epoxy that might be holding them together. The problem with adding a .002" shim (or anything like that) as a correction, it will not hold up. A stack of thin shims will eventually fail . . . just as a "suitable" shim with a .00anything" will always need attention.
The wedge can also go in further if IT is compressing. Old wedges were soft sometimes whereas newer ones are very nice ( since 2019 or so). Check your wedge for any deformation.

Another problem that CAN show up is the spacer that is fitted ends up being too thin (factory flirting with doing the right thing!! ). There again, thin is no good! At that point it's better to shorten the arbor to allow a "more correct" spacer. This is rare but has happened a couple of times with me.

Definitely, the endshake measurement should be constant after a "set in" which will happen with really heavy loads. It will stop and maintain though. The wedge will then go in slightly further. As with my personal open-top revolvers, a few cylinderfulls of top loads will settle the "fitted" surfaces and then be constant. To end up with a .002" endshake, I need to start with a "tight' .001" endshake for the '60's. The Dragoons maintain what they are set at at this point. With new 11° forcing cones cut, I don't believe they will move.

Mike

KingOfKindling said:

What do your shims look like? I try to avoid multiple pieces, but if I mess up, or am too lazy to fit something for the 15th time, It's nice to have a set of shims on hand. Bought a big assortment from triggershims.com a while back to fix an 1858 hammer issue, and they've been really helpful.

If you do something like this, you won't have a problem with stuff compressing.

View attachment 357240

A machine screw would have been easier, but I didn't have one on hand with a wide enough head. If your leading shim doesn't have a bevel on the front, the edges can compress. Better to have a larger beveled bearing surface, then you can just swap out thin shims until you get things perfect.

Click to expand...

Usually the end of the arbor well is not perfectly flat but dished in the middle . This leaves a rim perimeter for the actual bearing surface which is why shims compress and oval head machine screws, set screws or solid steel end plugs do not. I prefer the solid steel end plug an not drilling, tapping and threading the end of the arbor ahead of the slot to maintain full arbor strength.
Also if one has the means, making a new properly fitting tool steel wedge will pay big dividends in function. Most factory wedges could stand to be a bit thicker to fit more snugly vertically in the slot in my opinion, to help keep them from backing out instead of having to drive them in so tightly.. A couple bumps from a screw driver handle is adequate if the wedge is properly made, fit and hardened correctly.

Mike,
Thank you. I am getting some wild stuff on the posts so a bit of a hard time working through it. Has to do with formatting and such, working with admin to see if I can get it cleared up

Well this was with an unmentionable but 1 inch group at 25 yards and 6 shots hand rested, amazing. I should have gone home right after! I don't want any violations of course so if you want the details of the load PM me. And I don't have any ego in this, sure you can fake a picture, I am happy to get a 2 inch group and usually the best I do. 3-4 inch ones not uncommon and sometimes worse. So this was the stars aligning just right. I get that at times rifle shooting, get a 1/4 inch group at 105 yards but day in day out is 1/2 inch.