Lots of variables here Ed, your powder is probably ok. Different
bullet, charge weight, crimp?, primer and your mod 49 has a
1 7/8" barrel and the K frame mod 10 has a 2" barrel. All
loads that I have chronoed in a 2" K frame run faster than
the same load out of one of my J frames. Bullet seating
depth, cast or swaged, crimp can make a big difference. For
some reason some handloaders insist on taper crimping cast
bullets that have a substantial groove for a roll crimp. Is
your bullet plated? I just measured the barrel of my 37-2
and it's not even a full 1 7/8", more like 1 13/16". Don't
throw your old bottle of 231 away yet. The bottle of 231
used in these loads is older than yours. Maybe 231 just
keeps getting better as it ages. I might sprinkle a little in
my food and see if it works for me!