Adapting 38 loads to 357 cases

[cabezaverde]

I have a 38 special load that shoots well in my Security Six, and would like to adapt it to 357 cases to avoid cleaning the crud ring.

I saw a tip somewhere to increase the charge ~10%, but I thought I would solicit advice from the group.

Any input?

[WildmanJack]

Cabeza,
I have shot hundreds if not thousands of rounds of .357 downloaded to .38 loads and never had a problem!! Didn't want to shoot those hot loads so I just loaded to .38 powder specs and shot them !! Now maybe I was doing something wrong, but those rounds worked fine for me!!
Good luck..
Jack

[Dale53]

The best way to upsize loads from .38 Special data to .357 Magnum cases is to chronograph your .38 Special loads then match it with .357 Magnum cases. It will take a bit of an increase in the powder charge. This is a case where you can interpolate without getting into trouble (logic does not always apply and you MUST not do that with heavy loads).

Dale53

[Bass Ackward]

Dale has the "correct" answer for duplication. (if it works)

Each gun is different, even within the same manufacturers models, so there is no guarantee that that exact velocity point will agree with Professor Target.

I know that this isn't what you want to hear, but the best way is to just start with the same powder / charge with each load and work up.

The beauty of re-working the loads are that you NEVER have to worry that the load of a life time was just .2 of a grain away.

[theperfessor]

Some loads don't need much tweaking at all. It depends on your bullet. If you were using a 358156 crimped in the lower groove in a .38, then crimping it in the top groove in .357 will give virtually identical powder volume. Same thing with a 358429, crimp in crimp groove in .38, crimp over front of shoulder in .357. And some wadcutter loads with multiple lube/crimp grooves can give the same result, just make sure they have the same OAL. Obviously just seating the bullet in the same position relative to the case mouth would give more powder volume in a .357.

Just to add - I don't have any qualms about putting .38 loads in .357, but I NEVER put .357 level loads in .38 cases. I'd rather use the right brass than save a few cents on brass and wreck an expensive gun or hurt somebody. In my house any .38 load is safe to use in any .38.

[kelbro]

I have several loads that shoot identical in either 38 or 357 cases in my 6" 586. Not so lucky with the 2" snubby. You have to work them up (or down) like any other load but I would start at your 38 load just in case that's the sweet spot.