Use to shoot a lot of revolver in USPSA, pretty much a dead category now but still fun to play with the revolvers once in awhile.
160 gn round nose over 3 grains of clays or clay dot with give you a soft shooting load that will be close to power factor. Might have to adjust a little depending on your gun. Same brand brass and moons that fit that brass will make reloads much easier.
And to you original question, yes you can use for cowboy but I don’t think there’s a lot of advantage over 38 special.
LF.