Does it hurt the cylinder or rifling at all to go back and fourth between 357 mag and 38 special loads in the same shooting session? I am using the same bullet for both. (Hornady 125 grain JHP)??? I ask this because I was doing this out of my Ruger SP101 and found metal shavings while I was cleaning the gun. I now have a GP100 and don't want to take a chance of hurting the rifling...Thanks for the information

Nope, it doesn't hurt a thing, however, the .38 specials might build up a little carbon ring that will make the .357's fit tight. I just take a cylinder brush along, and knock it out when I switch to .357's.

Should have no affect at all, but why do it? Don't they shoot to different points? As to the dreaded carbon ring, a favorite topic of the gun writers, I have personally never experienced something like this hindering the chambering of a 357 mag. case. Perhaps because I clean my guns? Maybe after several thousand rounds of 38spl. without cleaning the chanbers one might experience this.
Peter.

Thanks guys.. I don't really ever have much of a problem with carbon rings. I do notice a the rounds going in a little tight as my reloads with HS6 have been really dirty. I will be switching powder as soon as this bottle is gone....

bloodhound, what loads were you shooting with HS6? I was shooting some 125gr JHPs with HS6 in a GP100 when it started showing pressure signs and the cylinder wouldn't turn easily.

Sputser... For 38Special I was using 5.7 grains of HS6 and a 158 Cast SWC bullet. For 357 I was using 10.1 grains of HS6 with a 125g JHP Hornady XTP. I like the 357 loads, I do not like the HS6 for light 38 Special loads (losts of unburned powder).. My Favorite 357 load so far is 12.3g of Accurate #7 with the XTP bullet.
I also shoot all these out of a 4" GP100