average cylinder gaps

[M. De Land]

I would like to ask folks to measure their cylinder gaps on new or unaltered percussion guns and some original guns for comparison and post their results. I'm not really interested in tightened up worked over gun measurements but rather what the factory produced then and now.This is easily done with a feeler gouge at half cock when the cylinder is not under pressure from the hand. Now a feeler gauge is not used by jamming it into the gap. The proper technique is to "feel" it when the blade makes sliding contact with both sides simotaineouly . Most guns, even solid frame will not be level around the clock so where really after the tightest spot measurement.
I think this will be both fun and informative.
My 60 Pietta was about .012 before the new wedge, the 62 police is .011 from the factory and I'll need to measure the 58 and post later.

 

[Jim in Wisconsin]

On my old Navy Arms/Uberti Remington, the .010 feeler gauge goes and the .012 doesn't.

 

[45D]

I took the challenge and as per request. I checked 6 revolvers from a customer. Two 1860 Colt 2nd gen Army's , two '51 Colt 2nd gen Navy's and two Colt 2nd gen 3rd Model Dragoons. I also have a NIB Whitneyville Dragoon ( Uberti) to "address " one of these days! The measurements were from .003" to .008" ( I pulled the cylinder back against the recoil shield for consistency since the hand spring would keep the cyl pushed forward . . . even with muzzle pointed up). I then tapped the wedge and every one of them changed ( of course I knew that would happen) so I think it's too much of a moving target to get any real consensus. Since I don't have an original on hand to check ( much less a pristine example to aliveat any wear/ abuse) I checked the only Pietta I have in the house. It's a brand new in the box customer's '60 Army. It's a 2021 build so knowing that I tapped the wedge to make sure it was in fully and it measured .003" !! That's a good number!! Of course I went ahead and measured my own open tops anyway ( my apologies since they have been "corrected" ) and they were where they were set up to be.
So, the obvious takeaway from this exercise is that the only way to have a consistent measurement is to have a setup that doesn't allow the wedge to influence the measurement.
I'm certain if I remove the wedge from all the revolvers I tested and put them back in fully, the Pietta and my "corrected " revolvers would measure what they did before while all the others would be rather inconsistent.

Mike

 

[45D]

I checked my Remington (Pietta) and it measured .003" with 0 endshake. My Pietta made Frontier (with 45acp cyl) came in at .007" with 0 endshake (bushing shimed).
Just FYI.

Mike

 

[M. De Land]

I checked my Remington (Pietta) and it measured .003" with 0 endshake. My Pietta made Frontier (with 45acp cyl) came in at .007" with 0 endshake (bushing shimed).
Just FYI.

Mike

Thanks Mike, good information ! I'm hoping some more folks will check the barrel gap at the wedge position they generally use. I've always set my open tops by feeler gauge in the gap or wedge depth protrusion to keep them consistent. Solid frame percussion guns I've liked .001 end shake and about .004-.006 barrel gap.
As the majority of the guns out there probably have short arbors I'm interested in what is actually being used as is from the factory.

 

[M. De Land]

On my old Navy Arms/Uberti Remington, the .010 feeler gauge goes and the .012 doesn't.

Thank you, I'm guessing many are in this range as well. I generally have set mine (open tops) up around the .005 -.006 when corrected for black powder use with .010 the max before correcting them.

 

[Stantheman86]

I honestly can't tell, I have never measured them

I eyeball it against light and I just shoot them

My question is, do BP revolvers really generate enough gas and velocity for a few .001 each way to make a difference, short of a horribly bad gap

Back when I was younger and dumber I fired an old Iver Johnson .22 with probably an 1/16" gap, no joke and it actually did ok on paper. Probably killed velocity but it worked.

 

[45D]

The biggest differences between a .0025" - .003" endshake and. 005" or bigger is efficiency and less "slide hammer" effect. Customers have always commented how much cleaner the revolvers shoot and the shooter themselves. Makes sense with more fouling going down the barrel and less out the side which also means more energy is being used to push the projectile since less is escaping. Mr. Bradshaw says endshake is the most detrimental force to a SA revolver (other than grenading it!!) and I agree, especially for an open-top revolver. In both cases, smaller is better.

Mike

 

[M. De Land]

The biggest differences between a .0025" - .003" endshake and. 005" or bigger is efficiency and less "slide hammer" effect. Customers have always commented how much cleaner the revolvers shoot and the shooter themselves. Makes sense with more fouling going down the barrel and less out the side which also means more energy is being used to push the projectile since less is escaping. Mr. Bradshaw says endshake is the most detrimental force to a SA revolver (other than grenading it!!) and I agree, especially for an open-top revolver. In both cases, smaller is better.

Mike

I'm gona give it a try and see for myself. Never to late to learn/try something new and possibly better. I sure like the idea of your manure catcher on the hammer Mike!

 

[45D]

I'm gona give it a try and see for myself. Never to late to learn/try something new and possibly better. I sure like the idea of your manure catcher on the hammer Mike!

You mean this?

It definitely keeps the action much cleaner. The "hook" on the end keeps cap frags from entering the action and keeps presenting them so you can dump them whenever.

Mike

 

[Bad Karma]

I honestly can't tell, I have never measured them

I eyeball it against light and I just shoot them

My question is, do BP revolvers really generate enough gas and velocity for a few .001 each way to make a difference, short of a horribly bad gap

Back when I was younger and dumber I fired an old Iver Johnson .22 with probably an 1/16" gap, no joke and it actually did ok on paper. Probably killed velocity but it worked.

There’s a really big difference in velocity. Ditto for cleaning and keeping them running. Excessive gaps allow fouling to accumulate on the arbor and can just stop a revolver in its tracks.

It’s raining today and I have nothing much to do so I’ll measure a few.

 

[M. De Land]

There’s a really big difference in velocity. Ditto for cleaning and keeping them running. Excessive gaps allow fouling to accumulate on the arbor and can just stop a revolver in its tracks.

It’s raining today and I have nothing much to do so I’ll measure a few.

The smaller gap does make sense when one chews on it a bit but until I started reading Mikes stuff I had always thought Black powder guns just wouldn't work with tight gaps. I've know for years that Dan Wesson guns were always set up with .002 but that was smokeless not BP and since most percussion guns I measured from the factory were closer to .010 than .003 I concluded they were supposed to be more open.
I'm curious to hear what some of your guns measure BK and thanks for taking the time to do it !

 

[45D]

Thanks M. De Land. With the "normal" SA having a bushing that keeps the cyl face from ever touching the barrel, it allows for fouling (of all kinds) to build up. The one advantage the open-top platform has is the fact that the cylinder does contact the bbl which acts as a built in self cleaning system and allows a .002" endshake if you want. The unmentionables using smokeless can handle .0015" - .002" .
The close endshake on cap guns also allows good insurance for ignition since the cylinder can't move "out of range" for the hammer to hit a cap. Much easier to set up a "safe to dry fire" to protect the nipples and still have reliable ignition.

Mike