Talyn
SAINT
The .257 Roberts Ackley Improved
The .250 Ackley Improved was developed by Parker Otto Ackley, P.O. Ackley, was an American gunsmith, barrel maker, author, columnist, and wildcat cartridge developer, that sparked considerable interest in improved cartridges.
According to P.O. Ackley, the modified 257 Roberts was likely the best improved round compared with the couple dozen or so factory cartridges he’d experimented with.
The two most popular "Improved" .257 Roberts cartridges are the Ackley and RCBS versions. They are quite similar except for the shoulder angle, which is 40 degrees for the Ackley version and 28 degrees for the RCBS version.
The Ackley Improved family of wildcat cartridges are designed to be easily made by rechambering existing firearms, and fireforming the ammunition to decrease body taper and increase shoulder angle, resulting in a higher case capacity. P.O. Ackley improved not only standard cartridges, but also other popular wildcats. Measured water capacities of a standard .257 Roberts case and fireformed AI cases, the difference was about 13 percent (60 grains compared to 53 grains of water).
The Hornady Handbook and Nosler Reloading Guide show maximum reloads for the .257 Improved (either version) achieving muzzle velocities (MV) of about 3600 fps with a 75 grain bullet, 3400-3500 fps with an 85-87 grain bullet, 3200 fps with a 100 grain bullet, 2900-3000 fps with a 115-117 grain bullet, and 2900 fps with a 120 grain bullet.
The Hornady Handbook and Nosler Reloading Guide show maximum reloads for the .257 Improved (either version) achieve muzzle velocities (MV) of about 3600 fps with a 75 grain bullet, 3400-3500 fps with an 85-87 grain bullet, 3200 fps with a 100 grain bullet, 2900-3000 fps with a 115-117 grain bullet, and 2900 fps with a 120 grain bullet.
The fifth edition of the Noser Reloading Guide shows that 43.5 grains of RL19 powder can drive a 115 grain Nosler Partition bullet (BC .389, SD .249) in an Ackley Improved case to a MV of 2672 fps; 47.5 grains of RL19 will take the same bullet to a MV of 2960 fps.
The .257 Ackley Improved is a fine performer, adding up to 100 fps velocity over its factory cousin. One of its advantages, Ackley noted, is the fact that .257 Roberts factory ammunition can be used in an improved rifle if necessary.
The .250 Ackley Improved was developed by Parker Otto Ackley, P.O. Ackley, was an American gunsmith, barrel maker, author, columnist, and wildcat cartridge developer, that sparked considerable interest in improved cartridges.
According to P.O. Ackley, the modified 257 Roberts was likely the best improved round compared with the couple dozen or so factory cartridges he’d experimented with.
The two most popular "Improved" .257 Roberts cartridges are the Ackley and RCBS versions. They are quite similar except for the shoulder angle, which is 40 degrees for the Ackley version and 28 degrees for the RCBS version.
The Ackley Improved family of wildcat cartridges are designed to be easily made by rechambering existing firearms, and fireforming the ammunition to decrease body taper and increase shoulder angle, resulting in a higher case capacity. P.O. Ackley improved not only standard cartridges, but also other popular wildcats. Measured water capacities of a standard .257 Roberts case and fireformed AI cases, the difference was about 13 percent (60 grains compared to 53 grains of water).
The Hornady Handbook and Nosler Reloading Guide show maximum reloads for the .257 Improved (either version) achieving muzzle velocities (MV) of about 3600 fps with a 75 grain bullet, 3400-3500 fps with an 85-87 grain bullet, 3200 fps with a 100 grain bullet, 2900-3000 fps with a 115-117 grain bullet, and 2900 fps with a 120 grain bullet.
The Hornady Handbook and Nosler Reloading Guide show maximum reloads for the .257 Improved (either version) achieve muzzle velocities (MV) of about 3600 fps with a 75 grain bullet, 3400-3500 fps with an 85-87 grain bullet, 3200 fps with a 100 grain bullet, 2900-3000 fps with a 115-117 grain bullet, and 2900 fps with a 120 grain bullet.
The fifth edition of the Noser Reloading Guide shows that 43.5 grains of RL19 powder can drive a 115 grain Nosler Partition bullet (BC .389, SD .249) in an Ackley Improved case to a MV of 2672 fps; 47.5 grains of RL19 will take the same bullet to a MV of 2960 fps.
The .257 Ackley Improved is a fine performer, adding up to 100 fps velocity over its factory cousin. One of its advantages, Ackley noted, is the fact that .257 Roberts factory ammunition can be used in an improved rifle if necessary.
