need a "how too" on reaming out a cylinder slightly ? .320 brit - 32 acp

brianthegunboy

brianthegunboy

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so here is the situation: i have recently acquired a antique webley copy in .320 british . now, the round itself has been out of production for many of years.
research has led me to try out 32 acp/32 auto. unfortunately the cases are just too big though. the chamber measures .326 where the 32 auto is .331. long story short is, i would like to ream the chambers out. this is so i could use the very abundant and cheap .32 auto.. how can i do this ? any help would be great
 
Be careful with this. .32ACP is a much higher pressure round than the .320CF / .320 British rimmed rounds and the old Webley may not handle the pressure well, especially if you remove metal from the cylinder.
Additionally, reaming this out to .32ACP may well turn your Webley into a 12.6 prohibited handgun. Chambering an antique handgun to a caliber that is on the prohibited list will void the antique status. There are several people on this forum that can provide you with additional information. Best to do more research first. Look through the Antiques forum for more info.
 
if you ream it out to 32 acp it will also chamber 32 s&w the 2 rounds are interchangeable in a revolver so it will no longer have antique status.

if you get a set of 32 colt dies you can resize 32 s&w or 32 acp down to .320/32 colt if you cant find 32 colt brass.
 
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rgbai said:
if you ream it out to 32 acp it will also chamber 32 s&w the 2 rounds are interchangeable in a revolver so it will no longer have antique status.

if you get a set of 32 colt dies you can resize 32 s&w or 32 acp down to .320/32 colt if you cant find 32 colt brass.
Click to expand...

32 colt isn't on the not-an-antique list? i thought it was? or is that 38 colt (short and long) only? bahh... stupid laws
 
Looking at the specs for the .320 from Wikipedia it appears that both the bullet and casing are already bigger in diameter than the .32 S&W or Colt rounds. So it's not a question of opening the chambers up. The rounds mentioned as substitutes are already smaller than the chamber by enough to produce problems of fit and sealing as well as accuracy.

The downside is that the next size case up, .32S&W Long and others of that same "family", have too big a case. But I'm wondering if some .32 Long cases could be machined down a little and still have a thick enough wall to work. It's a lot of work of course. But it would give you some better fitting brass until you can source some that works.

The other option is to find the proper reloading dies. Then "fire form" the .32S&W cases out to fit then only size them with the bigger dies used for the proper .320 Webley/Euro/Bulldog rounds. Once fire formed, and possibly annealed to reduce any residual stresses in the brass, the sizing to the proper size for the chamber shouldn't result in any long term issues with the brass. It just means that the small bullets used the first time around won't be that accurate and the small case size will result in a fair amount of blowby and case staining on the outside.

Because you're forming out the brass I'd also want to start with the bigger rim diameter of the .32S&W brass instead of the semi rim found on the ACP cases.
 
ok here is a thought .. if i use the 32 colt long trim them down and bore out my cilender to just slightly shorter cases than the restricted calibers , would that keep it antique ? if so i will call the cal "32 Canadian" :p
 
I can't comment on the legality of it. But I forgot to mention that to get any decent accuracy that you'll also need to find or make your own bullets. The .320 is listed as a .317 size vs the .312 to .314 bullets found more commonly for .32 caliber cartridges. It likely means you'd need to lap out a mold to allow it to drop at the proper size.

The way this is done is to cast a bullet in the mold then screw a wood screw into the back of the bullet. Then with a dollop of lapping compound in the cavity close the mold halves on the bullet and run the screw in a hand drill to lap out the mold. The bullet will only cut away a thou or two so you'll likely need to cast another lapping bullet after the first lapping operation to bump it up to the next size.

Another option would be to make up some sort of swaging mold where you can set the .313 size in place then whack it a good'un with a pin and hammer to bump the bullet out in diameter.

The last option is to order up a custom size casting mold.

With all this work needed in any event it seems like fire forming some .32S&W short cases to fit the stock chambers isn't a whole lot more work. And that way you don't run into any legal issues with the chambering changes.

In any event you would NEED a chamber reamer to do such a change. The chamber reamer having a ramped step part way out for a reduced size throat. It's not a straight through reaming job.
 
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