Walker cylinder gap

[knirirr]

I joined this forum very recently after having purchased a second-hand ASM Walker, hopefully to be able to research information on loads &c. One post I noticed mentioned the cylinder gap having been extended by using large charges:

http://www.thehighroad.org/showpost.php?p=6876504&postcount=16

Would anyone be able to tell me what the gap should be?

Hopefully I can manage 50gr (by vol.) of Pyrodex P; ~450g of it was supplied with the gun. However, I intend to purchase black powder as soon as some bureaucracy relating to its transport is sorted out - any recommendations on a suitable powder would be welcome.

Here's the Walker:

 

[darkerx]

What are you willing to use your gun for? (for hunting, you should use full loads of swiss powder, for target shooting, 35/40gr should be enough...etc.)

 

[knirirr]

Target shooting is all that's allowed here, and at my main range I'll be limited to 25m. Longer range shooting might be possible elsewhere, though.
Is there a minimum load to avoid an air gap in the cylinder?

 

[darkerx]

You HAVE to avoid any air left in the cylinder. But you can without issue put 15grains of black powder, then semolina or corn-stuff to fill the void, then a bullet which has to be in the very front of the cylinder (then some grease in front of the bullet).

 

[knirirr]

Thanks - I suppose that some experimentation will be required to find out exactly how much packing is needed to get the bullet in the correct place; I note that two varieties of wad were supplied, one much thicker than the other, presumably for smaller loads.

In the unlikely event that it doesn't rain heavily I'll get to try the Walker out in less than a week.

 

[junkman_01]

The bullet does not have to be at the very front of the cylinder, but peak accuracy will be obtained if you do.

 

[darkerx]

If you want to reduce the cylinder/barrel gap, you insert harder the wedge (I think it is the correct word). But Walkers (replicas) can handle the worst loads (black powder only... )

 

[knirirr]

I thought you would have known that.

Suspected, but certainly not known. As it happens my entire experience is with rifles (modern) and muskets; I've not used a revolver before and so have no experience of loading them.

but peak accuracy will be obtained if you do.

Ah, I see. Thanks!

 

[junkman_01]

darkerx wrote:

If you want to reduce the cylinder/barrel gap, you insert harder the wedge (I think it is the correct word).

If that is the way you adjust YOUR gap, your guns are NOT properly adjusted/setup. B/C gap is controlled by the arbor and barrel lug length, NOT the wedge.

 

[madcratebuilder]

darkerx wrote:

If that is the way you adjust YOUR gap, your guns are NOT properly adjusted/setup. B/C gap is controlled by the arbor and barrel lug length, NOT the wedge.

Colts with short arbors can let you close up the barrel/cylinder gap by driving the wedge in further. This is not what was intended by the original design and a indication of a poorly fit revolver.

One post I noticed mentioned the cylinder gap having been extended by using large charges:


Would anyone be able to tell me what the gap should be?

I would not be concerned with the seating depth of your round ball at this time. When you become more proficient with the revolver then you can experiment with seating depth and using fillers. Some shooters report better accuracy with the ball seated flush and others see no difference at all. YMMV

 

[darkerx]

I'm not too used to those terms... there is the barrel and the cylinder axis with a mortise and a tenon going through both of them. The depth of the tenon insertion will reduce the B/C gap (from no rotation of the cylinder, to .5mm gap). I see no reason to modify the lugs length (which will only enlarge the gap anyway...).

 

[darkerx]

A bullet which will be too deep in the cylinder will reach a high speed without gaining momentum (there is no riffling in the chambers...). When such a bullet will reach the barrel, it will be much more violent than required (bullet will hit the barrel... it will have a hard time taking the riffle correctly... energy will be lost... etc.).

It's much better to have the bullet pushed "gently" in the barrel at the very beginning of the pressure build-up, then accelerated within the barrel, while taking the riffle correctly.

 

[knirirr]

My concern about the gap between cylinder and barrel is that I don't know what loads the previous owner has been firing (the gun was sold on his behalf by a dealer so I couldn't ask) and therefore can't tell if it has been damaged already. I don't think it has, but as mentioned earlier I am inexperienced with revolvers.

 

[scrat]

Post this in the WALKER club. Cylinder gap. When hammer is down the cylinder should have a small amount of play. The gap will be different from one Walker to another. Pounding in the wedge is not the answer. Your wedge should be tight enough to allow free movement without binding. The most important thing to note is BATTERY. When hammer is pulled all the way back does the cylinder have free play or is it locked up. IT should be locked up in Battery position ready to fire. If it is then your good to go. IF it is not then you need to have it checked. Any other questions you have on the walker either pm me or leave it on the WALKER Club

 

[darkerx]

Hum... Interesting... I bought my walker new in box, and can remove or insert the wedge by hand (and can adjust from blocking the cylinder to .5mm gap). I bought a mallet anyway but almost don't use it.

 

[junkman_01]

I knew it! Your Walker needs proper fitting.

 

[makos_goods]

Darkerx this is how a wedge is to be used.

Darkerx,

The original Colt's pattern designs had the arbor hole in the barrel underlug cut to a depth that caused the arbor to bottom out in the hole. This is what set the cylinder gap, not using the wedge as an adjustment feature. Armi San Marco and Pietta usually have arbors of correct length, Ubertis almost always have an arbor that is too short. Uberti is taking manufacturing shortcuts to reduce costs and we have to come along behind them and correct them. Those of us that have been shooting Ubertis for a long time have different methods of correcting this condition.

Let me direct you to Pettifogger's excellent series that was published in the Cowboy Chronicle It is archived over on The Open Range, these are the two articles of interest.
http://www.theopenrange.net/articles/Tuning_the_Uberti_Open_Top_Revolvers_Part_3.pdf
http://www.theopenrange.net/articles/Tuning_the_Uberti_Open_Top_Revolvers_Part_4.pdf

The first two installments are also excellent as well as his write up on gunsmithing the Pietta Colt's reproductions.

I have three original Colt's revolvers and I can attest to the fact the arbors all bottom out in the barrel underlug. The wedge was intended to be simply a "locking" mechanism, no more.

I basically do the same thing Pettifogger does on my revolvers but I use a threaded button and try to match it to the arbor. I have the resources to do that and I am a bit anal, but I think Larson's solution is simple, inexpensive and meets the needs of 99.9% of the shooters.

I have some pictures somewhere, but you can barely tell that the button is even there, so I will direct you to some CAD models of the spacing button I use.
http://www.cascity.com/forumhall/index.php/topic,36113.msg462569.html#msg462569
http://www.cascity.com/forumhall/index.php/topic,36113.msg462482.html#msg462482

Two of my originals are well preserved original 1860s and I spent some time with them determining what the original intent had been for the design. One Pistol built in 1861 has a .009" cylinder gap, I have another produced in 1862 which is in even better shape and it has a gap which is probably .0105". A .010" feeler gage will go and a .011" will just start. I did some additional research and consulted with other 1860 owners and found their original pistols ran between .008" and .012". I have a Colt's shop manual for SAAs and they specify a .008" gap for the Generation 2 and later revolvers (that's using smokeless powder). There is also a reference in a copy of another shop manual I got from one of my former instructors who worked at Colt's for 40 years that the Gen 1 revolvers cylinder gap go/no-go gage was originally .008" to .010".

I finally "relearned" what they knew 164 years ago, a Colt's pattern revolver works best with a cylinder gap of about .008"-.010" for a cap gun and .006" -.008" for a cartridge revolver with a gas ring to control the end shake.

If you have any questions, just ask.

Regards,
Mako

 

[darkerx]

Hum... I don't like drilling in guns... but I can glue a brass button to avoid having to adjust manually the wedge after every cleanup of the Walker.

Thanks for your valued input.

 

[madcratebuilder]

A brass spacer is a simple and effective way to address arbor length problems. The Walkers like more barrel gap than the later Colts due to the larger contact surface between the cylinder and barrel. This was a issue Colt addressed with the Dragoon models, adding a large taper to the breech end of the barrel. This substantially reduce the contact area and reduce cylinder drag caused by the build up of powder residue.

 

[Hellgate]

I like .007" gap on all my Colt open tops.

 

[junkman_01]

I like .007250"

 

[Lunie]

I currently use a gap of 0.0000000000000000000209748603 ly (lightyears) on ALL* of my Walkers.



*I currently own limit as [x--> infinity] (1/x^2) Walker revolvers and reproductions. (So I own 0 Walkers, and I strongly suspect that my cylinder gap calculation has what I can best describe as a "astronomical" amount of rounding error.) But you get the idea.

 

[col.lemat]

anything less than 1 inch would be helpful. I like between 5 & 10 thouand