38-55 conundrum

[Distant Thunder]

Don,

It somewhat depends on two things, your velocity and how far you're going to shoot. I don't know what kind of velocity the .38-55 can get with BP, but 1200 fps is probably middle-ish. Then keeping in mind that I don't try to push the length to twist issue to the max here's what I believe are the lengths that should work for midrange shooting:

Bullet length for a .38-55 with a 1 in 14 ROT:

1100 fps 1.180"

1200 fps 1.230"

1300 fps 1.280"

The more you exceed these lengths the more instability you will see as the range increases and/or the winds come up, especially those nasty quartering headwinds.

Other than that, you pay your money and take your chances! Good luck.