I tried some Precision Delta wadcutters in a Model 60 and in my GP100 a couple years ago. Got severe leading in both guns (both chambered .357) very rapidly. I have been blaming it on the throats gauging .359 in the J frame and .3585 in the GP, causing blow-by and melting lead off the OD. Could the actual problem be the chamber length issue you describe?
Should I even bother trying to load the box of Hornady swaged HBWCs I have for revolver use, since mine are all .357?
I also have a 10-inch octagon Contender barrel in .38 SPL, but there's a good chance it has an unreasonably long throat, based on my reading about factory Contender barrel chambers. I haven't taken a cast yet.