Glad you asked this question. I am a 32-20 nut and have tried to collect every variety of vintage ammo since the 1930s for this caliber. All 32-20 ammo by Winchester and Remington since the 1970s is
safe in a S&W/Colt or any other original gun in good condition.
The rifle only loads were last loaded in the 1960s and are 80 gr
hollowpoints that resemble a FMJ with a tiny hole in the center (32-20 WHV, 32 WHV,etc were the names).

Nearly all 32-20 ammo will be listed as a "rifle" cartridge because
that is what it originally was and has nothing to do with
whether it can be fired in a pistol or the pressure.

The 100 gr loads or 100 JSP by Winchester or Remington
are all safe in your gun. The rifle only loads are/were rare
and are seldom seen now. They had a warning on the box
cautioning use in M73 Winchesters and pistols.

The following loads are safe:

32-20 Winchester Ammo by Remington : Pistol Ammo at GunBroker.com

32-20 Winchester Ammo, Cartridges, Ammunition : Pistol Ammo at GunBroker.com

32-20 WINCHESTER, NEW WINCHESTER AMMO : Rifle Ammo at GunBroker.com


The following should NOT go in your Colt/S&W

1950s
Western Super-X 32-20 HV Hollow Pt. Full Ctg. Box : Collectible Ammo at GunBroker.com

25-20 but 32-20 would be identical-last hi velocity made 1960s box
Western 25-20 60gr. Hi-Velocity : Collectible Ammo at GunBroker.com


Hope this helps. Please note that modern Remington will say High Velocity but the only loads Remington makes for the 32-20
anymore are lead loads that are like 32 S&W.....quite anemic.
Winchester only loads lead anymore either. Remington
did make a version of the rifle only load years ago and was labeled
HI SPEED not High Velocity and the bullet looks identical
albeit with a bit more point than Win.

The following is in stock and would be great for your gun
Winchester Super-X Ammunition 32-20 WCF 100 Grain Lead Flat Nose Box of 50 - MidwayUSA

Good Luck....32-20s are fun.