Anybody ever converted a Marlin or Winchest
I don't have any experience with having a lever action rifle reworked to shoot the .357 Maximum cartridge, but I have loaded .357 Maximum equivalent rounds for my .357 Magnum Rossi ('92 Winchester clone) which can be loaded into the chamber one at a time.
The standard .357 Magnum in a 20" barrel is a very lethal round, especially with 180 gr. LBT style cast bullets. They have a broad flat point and the seating depth is the same as a 158 gr. jacketed bullet which will give sufficient powder space to propel the heavier 180 gr. LBT bullet to 1,700 f.p.s. with no problem whatsoever.
About 4 years ago I got the bug to see what a .357 Maximum equivalent round would do in my Rossi's 20" barrel. In order to accomplish this, I would have to seat the bullet just barely into a .357 Magnum case to get the same overall cartridge length as the same bullet loaded in a .357 Maximum case.
In order to chamber the long round, the forward portion of the bullet needed to be reduced so that it would ride the top of the lands and thus allow the overly long cartridge to chamber. I solved this by running the 180 gr. LBT cast bullets nose first into a .349" sizing die for about .37".
I selected a published starting load for the .357 Maximum using a 180 gr. bullet with 296 powder. I loaded 5 rounds to the same overall length as the .357 Maximum with the modified LBT bullets and headed to the range. I single loaded each "torpedo" into the chamber and fired the 5 cartridges which had noticeably more pizaz than the standard .357.
With the sights all the way down, the bullets impacted in a 3" group
12" above the aiming point @ 100 yards. Velocity! I was surprised! The chronograph registered 2,080 f.p.s. average for the 5 shots! WOW! The cases extracted easily and there were no signs of excess pressure.
Yes. A .357 Maximum chambered lever gun would be a powerful package indeed!
aka Jack Christian SASS 11993 "I can do all things through Christ who strengthens me." Philippians 4:13
aka John Kort
Life Member NRA
.22 WCF, .30WCF, .44WCF cartridge historian