I have a London Navy Colt from about 1854 that does not group very well. Apart from the springs, it is all original. Could anyone suggest what I should do to assess where the problem may lie?
The pistol was last shot some 20 years ago before I acquired it. The owner had tried varioius loads with standard ball without any real results (20" at 20yd) and gave up. I acquired it at modest cost as a wall hanger, but now wish to put it on my firearms license and shoot it.
The rifling seems good and deep and the barrel has no movement. Cylinder locks up very tight.

As with ALL guns, check the crown for ANY sign of damage and repair.

Thaks for the advice regarding the crown. This was done at the time it was shot some 20 years ago - it appears to be at 60 degrees. I will put it in my lathe and give it a light cut with a sharp tool.
Just pushed a lead ball through the barrel - went in fine, then slightly tight. One inch later quite loose for about one inch, then reasonably tight to end. Outside of barrel seems OK. Is this how it should be?

quote:

Originally posted by jerry o'brien:
Just pushed a lead ball through the barrel - went in fine, then slightly tight. One inch later quite loose for about one inch, then reasonably tight to end. Outside of barrel seems OK. Is this how it should be?

No. Ideally you want the lead ball to feel the same from the breech to the muzzle. If a loose spot in the bore is going to have a shot at being non-problematic, then it has to be far enough from the muzzle to allow the bullet to regain it's form.

What is the diameter of the chambers, relative to groove diameter ? Chambers should be at least as large as the grooves. The ball should be large enough to swage quite snuggly in the chamber. A bit of light grease should cover the ball at the front of the chamber, and a fiber or felt wad between ball and powder helps.

Thanks Kaboom, I think you may have loccated my problem. The chambers are about 0.372" at seating depth (measured with a caliper). I locked the caliper and was nearly able to rotate it in the bore. Fron the bottom of one groove to the other was about 0.385". The mould I was given with the pistol is "spherical ball, diameter .376".
Would using conical shaped bullets help, what diameter of bullet should I use and should I lightly ream the chambers?

These guns shot round balls, which you know, that were approximately 0.375" diameter. However, the real secret is to get the round balls about 0.003" larger than the chamber throats/ball seating area. That is done so that you will shave a little lead ring off the ball as it seats and get a good, tight fit. The tight fit allows less flash through and keeps the ball in place under the forces of recoil.

You do not say what powder you are using. You should only use FFFg honest-to-god real Black Gunpowder. No substitutes, please. Part of that has to do with the way BP burns: It detonates and you have all of your pressure generated while the ball is still in the cylinder. If this is done, most of the time the ball will upset to obturate the full size of the bore, even if the bore is slightly oversized. That is just one of the reasons not to use any alloy, but only pure lead.

What are you using for a lube over the bullet? I have extrememly good luck with one of the incarnations of 1000+ in a jar. The jar stuff is a little stiffer than the stuff in a tube.

Hope that helps.

Thanks Geo, that was very helpfull. The powder used was FFFg and the lube was one of the previous owner's own recipies - it probably was up to spec.The balls were cast from scrap roofing lead.
I am considering opening up the cylinders to 0.375 - I have found an unused three eigths Presto reamer and I have a decent Milling machine. I could then use a slightly larger ball (say .377/8). What would your opinion be on this?

Jerry,

If you use a reamer 0.375" then your resulting holes should be so close to that, that a round ball would never know the difference. However, it would be a mistake to get the balls too small, so mike the resulting holes and get a ball for the +0.003" number.

BTW, as I shoot several Colt revolvers, I am aware of the fit and looseness of the barrel to the frame and the fit/tightness of the wedge. Any room to improve there? Those were some of the wear spots, traditionally.

You are right when you say that the lube you are using is probably up to the job, byt try some Crisco just for curiosity's sake. Crisco is great in cool weather, but does not hang around in hot weather.