Awaiting my first GP100 (also first 357). Is there any reasoning to running a bunch of 38 special through before any mag loads for break in? Maybe I'm over thinking this?
Or, if you so desire:
Recommended Cleaning Procedures « Montana X-Treme
Click on the "PROFESSIONAL NEW BARREL BREAK-IN PROCEDURE" link.
I just shot mine, then cleaned afterwards.
I would like to point out, .38 specials are shorter, but we know that obviously...But, shooting .357 after .38 will provide extra "baking in" of the shorter .38 crud ring... food for thought