Performance
By 1970 Winchester was forced to deal with the clumping of the compressed powder charge which had been resulting in improper ignition and poor performance. Winchester's remedy was to lessen the compression of the powder column. The result was a .458 Winchester Magnum that was now attaining only about 1,950-foot-per-second (590 m/s). This was 200 ft/s (61 m/s) below what Winchester's original design specifications intended. The .458 Winchester Magnum was originally supposed to duplicate the performance of the .450 Nitro Express which could fire a 500 gr (32 g) bullet at 2,150-foot-per-second (660 m/s).
On the other hand, the .458 Lott is designed to provide about 200–300-foot-per-second (61–91 m/s) more velocity than the .458 Winchester Magnum. The performance goal does not just match but exceeds the original performance specifications of the .458 Winchester Magnum. The cartridge is capable of firing a 500-grain (32 g) bullet at 2,300-foot-per-second (700 m/s) from a 23-inch (580 mm) barrel such as the Ruger M77. This capability easily exceeded the performance that was expected of the .450 Nitro Express and the .458 Winchester Magnum. The Lott cartridge was a distinct step up from the .458 Winchester Magnum and the .450 Nitro Express cartridges. The .458 Lott is also considered a better cartridge for dangerous game hunting that the .470 Nitro Express when judged by its effects on big game.
Due to its development and purpose, the performance of the .458 Lott is often compared with that of the .458 Winchester Magnum. This is inevitable as the latter was the cartridge which the .458 Lott was designed to replace.
| Cartridge | Criteria | Muzzle | 50-yard (46 m) | 100-yard (91 m) | 150-yard (140 m) | 200-yard (180 m) | 250-yard (230 m) | 300-yard (270 m) |
| .458 Winchester Magnum Hornady 500 grains (32 g) DGS | Velocity | 2,140 ft/s (650 m/s) | 2,007 ft/s (612 m/s) | 1,879 ft/s (573 m/s) | 1,757 ft/s (536 m/s) | 1,641 ft/s (500 m/s) | 1,531 ft/s (467 m/s) | 1,429 ft/s (436 m/s) |
| Energy | 5,084 ft·lbf (6,893 J) | 4,472 ft·lbf (6,063 J) | 3,921 ft·lbf (5,316 J) | 3,428 ft·lbf (4,648 J) | 2,990 ft·lbf (4,050 J) | 2,603 ft·lbf (3,529 J) | 2,267 ft·lbf (3,074 J) | |
| .458 Lott Hornady 500 grains (32 g) DGS | Velocity | 2,300 ft/s (700 m/s) | 2,162 ft/s (659 m/s) | 2,029 ft/s (618 m/s) | 1,900 ft/s (580 m/s) | 1,777 ft/s (542 m/s) | 1,660 ft/s (510 m/s) | 1,549 ft/s (472 m/s) |
| Energy | 5,873 ft·lbf (7,963 J) | 5,190 ft·lbf (7,040 J) | 4,568 ft·lbf (6,193 J) | 4,007 ft·lbf (5,433 J) | 3,505 ft·lbf (4,752 J) | 3,058 ft·lbf (4,146 J) | 2,663 ft·lbf (3,611 J) | |
The .458 Lott is able to attain over 2,300-foot-per-second (700 m/s) with a 500-grain (32 g) jacketed bullet at safe pressure levels from a 23–24-inch (580–610 mm) barrel. In comparison, many ammunition manufacturers load the .458 Winchester Magnum to velocities between 2,050–1,950 ft/s (620–590 m/s). Hornady's Superformance ammunition being an exception which uses powder blends which at present remain proprietary. The .458 Lott is capable of reaching a velocity of 2,150-foot-per-second (660 m/s) with the 600-grain (39 g) bullet which is greater than the velocity reached by Hornady's 500-grain (32 g) Superformance .458 Winchester Magnum ammunition. With lighter bullets of 300-grain (19 g) it is able to achieve a velocity of about 2,850 ft/s (870 m/s). These energy and velocity values provide the .458 Lott cartridge a gain of between 50–100 yd (46–91 m) over the .458 Winchester Magnum in distance. This performance increase provides better penetration and stopping power than the .458 Winchester Magnum against dangerous game.
However, the mono-metal bullets fall short of this velocity threshold due to the need to seat the bullets deeper owing to the length of the bullets and the need to stay within the maximum overall length specification of the cartridge. This is because the lower mono-metal bullets have a higher length to weight ratio than conventional bullets. Manufacturers such as A-Square have chosen to load slightly lighter bullets 465-grain (30.1 g) instead of the 500-grain (32 g) bullets.
The straight tapered case of the .458 Lott provides greater flexibility in reloading to lower velocities than bottlenecked cartridges. The ability to reload ammunition to lower velocities with lighter bullets can provide shooters with ammunition with less recoil than the full power .458 Lott ammunition. Nyati Inc., a big bore ammunition manufacturer, has taken advantage of this flexibility and offers ammunition featuring a 500-grain (32 g) copper jacket bullet at 1,100-foot-per-second (340 m/s). They also offer intermediate power ammunition for the .458 Lott as well.
Handloaders can take advantage of the wide range of bullet of useful weights are available in .45 caliber for the .458 Lott cartridge. Bullets ranging from 300–600 gr (19–39 g) can be loaded for the Lott cartridge. This, together with the ability to load the cartridge to lower power levels, easily adds to the versatility of the .458 Lott. .458 Lott velocities range from 3,000 ft/s (910 m/s) with the 300 gr (19 g) bullet and 2,150 ft/s (660 m/s) with the 600 gr (39 g) bullet. Spitzer bullets with better ballistics such as the Barnes X or TSX bullet provides better down range performance over the more conventional .45 caliber (11.6 mm) bullets. The .458 Lott does well with hardcast lead bullets. With these bullets the Lott can be loaded to the power level of the original .45-70 Government cartridge. which was a 405 gr (26.2 g) bullet at 1,330 ft/s (410 m/s).
What the .458 Lott lacks in velocity and energy compared to the .450 Rigby or the .460 Weatherby Magnum, it more than makes up for by virtue of its versatility. Larger volume cases such as the .460 Weatherby Magnum do not do well with powder charges below the recommended minimums. This is due to the erratic ignition and hangfire issues experienced when large capacity cartridges are loaded with small powder charges. The Lott has no such issues and takes well to lower powder charges.
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