This might seem like a nit-pick, but what is the consensus on cylinder gap on percussion revolvers in relashionship to accuracy? Does a wider gap give poorer accuracy? Even with the (new) wedge driven all of the way in on my 1861 Navy I still have a cylinder gap that's quite a bit greater than my other percussion revovlers, some of wich are too tight (i.e.. cylinder won't turn because of binding with rear of barrel) with the wedge in too far. The gun isn't as accurate as my other, "tigther" pistols. Could an excessive gap be the cause of this, or does cylinder gap have little to do with overall accuracy? Can anything be done to decrease cylinder gap on a Colt style percussion revolver? What does everyone else think?
Cylinder gap and accuracy
- Thread starter Dithsoer
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Sgt.Dusk
Member
I think the barrel itself makes the gun accurate, the gap only reduces the power and you may experience that bullets drop a lot more when shooting long distances. But then...there is some blast through the gap immediately after ignition which may make your gun "jump" before bullet leaves the barrel...and then there are million other things with revolvers that cause inaccuracy....
unspellable
Member
cylinder gap
Consistency in the gap from one chamber to the next will be more important than the overall gap itself unless you have a ridiculously wide gap. A black powder revolver should have a gap between 0.006 and 0.010 inch. At 0.012 inch it will start spitting. Less than 0.006 and it may bind up due to fouling.
Consistency in the gap from one chamber to the next will be more important than the overall gap itself unless you have a ridiculously wide gap. A black powder revolver should have a gap between 0.006 and 0.010 inch. At 0.012 inch it will start spitting. Less than 0.006 and it may bind up due to fouling.
arcticap
Member
It's pretty well established that when the chamber diameter has closer tolerances to the bore diameter, it helps to create better accuracy.
That and the dimensions of the forcing cone...
That and the dimensions of the forcing cone...
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Roswell 1847
member
I turn the cylinder face true and on a couple of my BP revolvers I've reduced the cylinder gap by filing a bit off the mating surface of the barrel lug (thats the lower rear portion of the Colt CB pistol barrel where it meets the front of the frame) then making a new barrel latch.
You often have to either file down the two pins sticking out of the frame or drill the holes in the barrel lug deeper.
I learned to do this by putting poor quality repro Colts into good operating condition.
My 1851 has near zero cylinder gap but doesn't bind. The cylinder face is true and polished so fouling just scrapes away, also little powder gases escape, also I use crisco rather than wads so the fouling remains soft.
I have a spare cylinder and generally wipe down and regrease the arbor before changing cylinders and/or reloading the cylinders.
I suppose if I didn't wipe away fouling between reloads it might build up eventually.
You often have to either file down the two pins sticking out of the frame or drill the holes in the barrel lug deeper.
I learned to do this by putting poor quality repro Colts into good operating condition.
My 1851 has near zero cylinder gap but doesn't bind. The cylinder face is true and polished so fouling just scrapes away, also little powder gases escape, also I use crisco rather than wads so the fouling remains soft.
I have a spare cylinder and generally wipe down and regrease the arbor before changing cylinders and/or reloading the cylinders.
I suppose if I didn't wipe away fouling between reloads it might build up eventually.
Roswell
I've considered doing the same thing to take up some of the space but how do you ensure that you are filing the mating surface precisely flat (I presume that the area filed is where the holes are that the two frame pins enter)? I'd try it but I'm afraid that I'd get one side slightly lower than the other.
Oh, and what do you mean by the barrel latch? And did you learn about this procedure from someone/somewhere else or just figure it out yourself? Did you get it right on the first try?
I've considered doing the same thing to take up some of the space but how do you ensure that you are filing the mating surface precisely flat (I presume that the area filed is where the holes are that the two frame pins enter)? I'd try it but I'm afraid that I'd get one side slightly lower than the other.
Oh, and what do you mean by the barrel latch? And did you learn about this procedure from someone/somewhere else or just figure it out yourself? Did you get it right on the first try?
Roswell 1847
member
I'm pretty skilled at making parts by hand.
You can use the spring from the old barrel latch if you remove it carefully its just pinned in place.
If you aren't up to making a new latch you can use a punch to upset the metal on each side ant the rear of the latch where it contacts the barrel or at the center of the front where it contacts the inside of the Cylinder pin/arbor slot.
Use the punch on both upper and lower surfaces. If the latch is not hard, and few of the replica latches are hard, then the first time you tap it home it will size itself and flatten the bulged surfaces. After firing a few full power loads it will set itself properly and won't be dificult to remove and replace.
Also many replica guns have ill fitting latches that bind at the rounded corners of the slot and dont even contact the place where they are supposed to in the center of the pin.
Those will appear to be tight fitting but when fired the gap opens up with each shot. When they wear in they are loose as a goose.
The inside surfaces of the barrel lug where it faces the frame are often left rough with deep machining marks. Usually if you just carefully file these flat and smooth you'll have already removed several thousadths of an inch, same goes for the mating surface of the receiver though its difficult to do anything about that unless you want to pull and replace the pins. I've done that also, not hard for me but not something you want to try unless you are confident of your skills.
I could show you much easier than I can tell you.
Invest in a good selection of jewelers files.
PS
Some cheaper replicas have oversized openings in the barrel lug, or undersized arbors, If the cylinder arbor is a loose fit then tightening the latch cocks the barrel upwards and the cylinder binds on the top.
If the fit is very loose you can shim it with either a very thin brass shim or a piece cut from an aluminum piepan.
I just make a new cylinder pin sized to fit properly.
You can use the spring from the old barrel latch if you remove it carefully its just pinned in place.
If you aren't up to making a new latch you can use a punch to upset the metal on each side ant the rear of the latch where it contacts the barrel or at the center of the front where it contacts the inside of the Cylinder pin/arbor slot.
Use the punch on both upper and lower surfaces. If the latch is not hard, and few of the replica latches are hard, then the first time you tap it home it will size itself and flatten the bulged surfaces. After firing a few full power loads it will set itself properly and won't be dificult to remove and replace.
Also many replica guns have ill fitting latches that bind at the rounded corners of the slot and dont even contact the place where they are supposed to in the center of the pin.
Those will appear to be tight fitting but when fired the gap opens up with each shot. When they wear in they are loose as a goose.
The inside surfaces of the barrel lug where it faces the frame are often left rough with deep machining marks. Usually if you just carefully file these flat and smooth you'll have already removed several thousadths of an inch, same goes for the mating surface of the receiver though its difficult to do anything about that unless you want to pull and replace the pins. I've done that also, not hard for me but not something you want to try unless you are confident of your skills.
I could show you much easier than I can tell you.
Invest in a good selection of jewelers files.
PS
Some cheaper replicas have oversized openings in the barrel lug, or undersized arbors, If the cylinder arbor is a loose fit then tightening the latch cocks the barrel upwards and the cylinder binds on the top.
If the fit is very loose you can shim it with either a very thin brass shim or a piece cut from an aluminum piepan.
I just make a new cylinder pin sized to fit properly.
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