I got my used contender with a 357 mag barrel in 1975 or so while I was still in high school.
I now have 2 frames, a number of barrels that do not get much action and my current regular shooters:
7.375" Stub tube 30 ACP (a.k.a my pop gun, shoots great with a BLL coated 55 gr nlg over 1.7 gr Titegroup for 890 fps)
7 TCU 10" (my newest, for IHMSA standing & production)
30 Herrett 14" (IHMSA unlimited)
357 mag (8.5" octagon to end of rifling, has a hot shot choke I never use)
The 357 barrel shoots good with any 38 or 357 load I feed it and does not accumulate any leading with loads that cause leading in my other guns. I use it a lot for standing practice while "burning up" ammo that I decide not to shoot in other guns.