The CPA 32-20 uses the same groove diameter barrels as the 32-40 in the .320 range and thus one can use the same bullets for both and their response to your question should now make allot more sense to you.

JLouis

The neck on the CPA 32/20, should be in the .342 range and should hold a .320 - .322 base band, ok.

Your concern should be the powder charge, when you reduce the case capacity by putting the bullet inside the neck. 

My suggestion would be to start at subsonic velocity's with your lightest bullet. I'd start with ~7.0 gr of the common powders like 4227, Enforcer and H110, or 300MP. 300MP would give the lowest pressures.

Use Remington cases, if you have them, all the others are weaker, Starline is probably second in strenght.

Frank

I'am actually going to try and stuff the case full of 2f BP . Since the chamber will be made like I'am going to breech seat the 32-40 bullet should be seated out further in the 32-20 case, any thoughts ? Thanks

Brudford01 wrote on Mar 18^th, 2018 at 4:33pm:


I'd have to see the chamber drawing of the 32/20 in order to tell you if that is possible. The standard type 32/20, wouldn't allow it.

Frank

Brudford01 wrote on Mar 18^th, 2018 at 5:24pm:


"Horrible" might depend on a number of variables and type of shooting, although "horrible" might be right for bench rest. IF you use a good bullet designed for BP and cast "soft" and plenty of excellent BP lube, as well as Swiss 2F or 3F, it is not unreasonable to expect "decent" groupings. Just substituting BP, even Swiss, for nitro powder I would expect horrible results for more than a few shots.

There is a shooter that posts here often that uses a .308 cal 10" twist barrel (if my memory is correct) with 150-175 grain bullets and BP to get quite good groups for short range (200M?) prone matches
MartiniBelgian -- is his correct log on. Need to do search that goes back a few years to find his relevant posts.

CPA sells dies for fixed 32-20CPA cartridge.  I'd suggest getting the dies and then load your fixed rounds.  Might save yourself a lot of work and heartburn. 
Rich

Brudford01 wrote on Mar 18^th, 2018 at 5:24pm:


I think understanding what that chamber design is like would be helpful. I have one myself and I know what it is. You can shoot BP. It will be accurate. BUT, you may just need to have a mold made to get the best out of it. 
For sure you will not be getting 1250 - 1425fps out of 210gr. bullets with black.

You can shoot to 200yd by using a purpose built bullet; lighter than 200gr with a short body, tapered and longer nose. I do not know offhand what combination of bullet weight and powder charge (FFFg Swiss) it would take to make 1200fps give or take. I have not tried. 

If you do, please let us know. I might try something like that someday with mine too. 

Remember,  these are NOT 0.313" barrels. They are real 32's and twisted for longer bullets.