.357 Magnum in a Rifle
Date: Apr 01 2012
The .357 Magnum is a useful and fun cartridge when fired from a revolver. Shot from the longer barrel of a rifle, though, the .357 shows a pronounced improvement in velocity and trajectory. I thought that higher velocity was everything I wanted when I started handloading a variety of powders and bullets for a .357 Magnum Uberti Lightning Short Rifle pump action with a 20-inch barrel. As it turned out, the best part was loading and shooting lead-alloy bullets in the fast-cycling Lightning.
The chambers in a .357 revolver’s cylinder offer quite a bit of leeway in what they accept in cartridge length and bullet profile. A rifle’s action demands a more exact cartridge length. A .357 Magnum cartridge over the established 1.590-inch length will not fit or cycle through the Uberti’s action. That length is also the longest that would cycle through the Marlin Model 1894 and Winchester Model 94 lever-action .357s I’ve shot in the past. The Uberti doesn’t have a feeding ramp at the entrance to its chamber, and bullets with a protruding shoulder catch on the bottom of the chamber mouth. Shooting jacketed bullets through the Uberti isn’t a problem, because they don’t have an abrupt edge from the nose back toward full diameter; but swaged lead semi-wadcutter bullets and bullets cast from moulds like the RCBS 38-150-SWC and Lyman 358156 refused to enter the chamber.
I resolved the problem by shooting bullets cast from an RCBS 38-158-CM mould. This bullet has a fairly long nose that merges smoothly to the bullet’s full diameter and feeds slickly through the Uberti pump.
I tried bullets cast from an LBT 358 200 FN mould, but that bullet seated in a .357 case with the mouth folded in the bullet’s crimping groove measured 1.641 inches in length, a bit long to cycle through the Uberti’s action. I single loaded cartridges by hand into the chamber, and they shot great and had an average muzzle velocity of 1,246 fps. The bullets could be loaded in .38 Special cases, and the cartridges would be short enough to fit; but that would reduce the velocity of the heavy bullet. For a high-energy load, it’s probably better to shoot 158-grain bullets with their 500 fps of additional velocity.
The Uberti’s 20-inch barrel and closed breech fired various bullets somewhat over 800 fps faster than a revolver with a 4-inch barrel. For example, the Uberti shot Sierra 125-grain JHC bullets 818 fps faster than a revolver with the same 22.0 grains of Power Pro 300-MP. The same load of H-110 shot a Sierra 140-grain JHC bullet 695 fps faster from the Uberti than from a revolver. The Uberti gained 622 fps with Hornady 158 FP-XTP bullets over Power Pro 300-MP. The LBT 200-grain cast bullet gained 309 fps shot from the 20-inch barrel compared to the 4-inch barrel. These velocity gains translate into twice the bullet energy and half as much drop out to 100 yards. Blue Dot, H-110, Lil’Gun and Power Pro 300-MP provided the highest velocity with jacketed bullets from 125 to 158 grains. Alliant Power Pro 300-MP registered the fastest speeds across the board. Hodgdon Lil’Gun was a bit faster with 158-grain bullets. However, Hodgdon’s 2012 Annual Manual lists loads for Lil’Gun only with 158-grain and heavier bullets. Power Pro 300-MP also provided the most even velocities, although all the powders used were pretty consistent with standard deviations of 20 to 40 fps for five shots.