STAINLESS! ? ! ? That doesn't sound very cowboy'ish.....
I just put about 40 rounds of .38 through my own blued .357 last night along with a few .357Mag. The bullet shape on these were flat point round nosed instead of the SWC's I used before. With the rounded shape it fed as fast as I could pull the lever.
On top of that I'm sure that ol' zeek bindertwine is right about the advantages of slickening up the insides to both cycle faster and more easily and deal with any ammo fussiness. There's a good writeup out on the web for doing just this for the Puma. I found it some time back and printed it off but it came up quite easily using google and the right keywords.