Re-crowning an antique S&W

[Exmilcop]

Up here (Canada), good functional antique pistols are very pricey. I have a line on a nice 1st. Mod. DA in .44 Russian, but there's a problem. At some point in its life the barrel took a major knock and the dent actually intrudes into the bore at the crown. I don't think I have to explain what that means. If I purchase it, I have 2 options as I see it. Option 1 is to get a machinist to put it into a milling machine and use an end mill to counter bore the barrel to the sound rifling. Option 2 is to have a gunsmith try to re-crown. As I don't actually have it in my hands, I don't know the extent of the damage but the price is very decent due to the damage. I'm looking for a good shooter more so than a high end collectible so doing mods to the pistol, though regrettable, may be necessary. Any advice would be most appreciated.

 

[steelslaver]

First thing I would do is have someone with a set of pin gauges drop the largest size that would move in the bore in from the frame end with the barrel pointed down and see just where it hung up. That would let you know just where the deformation in bore begins. Knowing that would tell you just how far in from muzzle you need to go to fix the problem.

Pin gauges are short hardened steel cylinders that are exact in dia. and increase in dia by .001

Just inside the muzzle you might be able to clean it up with just a re crown. If not a groove OD reamer or 4 flute end mill just deep enough to clean out the restriction. 7/16" is .4375 11mm is .43307. I only have fractional reamers and end mills but, looked and you can get an 11MM reamer or end mill for around $20

Myself I would be tempted to make a hardened pin say 1" long of land dia. with a slight taper on one end. Drop tapered end in bore from frame end then stack more pins in behind it until the last one showed in frame window. then press the first tapered pin though the restriction and see what happens. If the damage wasn't to bad it might push displaced material back in place. It would not make anything worse. You could take 2 pieces of say 3/4" flat bar and match drill 2 1/2" holes in them about 3" apart stick on in frame window behind the pin still protruding and the other in front of muzzle. The on in front of muzzle would need a 7/16" hole in the center to be lined up on the bore. Then using long 1/2" bolts or all thread on each side and tightening them evenly press the land diameter tapered slug though the restricted area. If the deformation was not too bad you might just need to fire lap it a couple of times and then clean up the crown a bit. Worst that could happen is it would destroy the land where it was deformed and you would be back to reaming it out. But, what was pushed in should be able to be pushed out.

I have a fairly nice first model double action 44 Russian top break and they are not target guns to start with, especially using double action.

 

[steelslaver]

There is another option. How long is your barrel? The front sight sits in a little slot and is held in by a cross pin. Remove sight, cut barrel right behind original slot crown, cut new slot, install sight and drill and install cross pin.

I know you have some rules up there on barrel length but no idea on how that applies to antique guns. If yours is a 6" you would be able to stay over 4 1/4" a 5" might end up a bit close.

 

[Exmilcop]

Thank you both, but wouldn't it be simpler just to use an end mill? Alternatively, maybe even just a cone shaped grinding bit in a drill press. I spent most of my adult life as a carpenter/cabinet maker and though I'm pretty tool handy, metal working is not my strong suit. If I buy the pistol, I'm going to talk to folks I know about finding a good machinist.

 

[WR Moore]

The problem is centering the end mill or other cutter* up with the bore. Depending upon where and how bad the ding is, a good machinist could manage to center the end mill on the outside diameter of the barrel. How close that is to the bore center is a possible issue. There are hand tools that allow you to re-cut the crown, but they use a pilot in the bore, so the ding would have to be removed before use.

There is another way, pull the barrel and re-crown on a lathe. That would also remove the ding.

*If the ding isn't too deep, a ball end mill might remove it without making much visible difference in the crown.

 

[Hondo44]

How large is the ding; how far into the bore does it extend?

Does it affect the groove or the land or both?

Sometimes if the damage is small enough, all the high tech machinery is not needed. Small dings in the crown that extend into the rifling can be honed smooth by hand. I've fixed a few like that with no loss of accuracy. You'd still show a ding in the crown but no doubt the gun has a few other dings in various places after all these years anyway. The originality of the gun would be maintained as opposed to shortening the barrel, back boring it, etc.

I believe steelslaver's idea is the best method and least invasive. It pushes (swages) the upset or displaced metal back to where it belongs.

 

[Exmilcop]

Thanks to all of you for your input, but I've opted not to buy the pistol. I've been offered another one that may be cosmetically poor but mechanically excellent. I'll probably go that route.