The .32 H&R Magnum is a good choice for people who are recoil sensitive, and is a good plinking round in the Ruger Single Six (though expensive for a non-reloader). .32 ACP can be fired in a .32 Magnum chamber (also in .32 S&W and .32 S&W Long chambers), but the rim is too small for good support and can give extraction problems. It is also too thin and there will be excess headspace, but that is seldom a problem in low power ammo.
If a lighter load than the .32 Magnum is desired, both the .32 S&W and the .32 S&W Long can be used (just like the .38 Short Colt, .38 Long Colt, and .38 Special can be fired in a .357 Magnum chamber).
Jim