Several years back I traded into a m25 83/8 that was in 95%+
condition. I had two boxes of factory Rem RNFP lead that I wanted to shoot up to get the brass. Me, Bro and a buddy shot
up the 100rds. Gun shot outstanding, even buddy who is not much of a pistol shot did well with it. Then loaded 242 cast WCs
solid base at 750fps and again they shot well, we were shooting
50'. Then I got Speer WCs and loaded them at 750fps. The three
of us fired 6 each in turn. Me first, they shoot good, Bro second
his shots were not quite his normal, buddy shot and did lousy
we didn't pay much attention to that because he is lousy shot.
That's 18rds at 750fps. When I started my second 6, my shots
were wild. I thought sight had come loose. Upon inspection the
barrel was leaded terrible. Almost like a foil coating, it came out
fairly easy. Shot no more of them. Then I bought a 19 with a
bunch of components with it. Speer swaged bullets among them.
They did the same thing in the 19 at around same velocity but
not as bad. I have shot a lot of Hornady lead bullets in several
different 38 & 357s and had no problems at all. I have run them
at 850-900fps no leading. I don't know how slow you would have
to run Speers to avoid leading. I cast WCs for my S&Ws and I
don't get carried away on alloy. I make them soft as practical and
I've never had a leading problem, this refers to LV target loads
which is about all I shoot in S&Ws. I have a Ruger SA for full
power mag loads that is my deer pistol.