.460 Rowland

level performance with a compact 1911 design autoloader. In 1996, Rowland worked with Starline Brass to finalize the physical dimensions of the cartridge, then later with Clark Custom Guns to design a conversion kit for specific versions of the 1911. First production shipments of ammunition and conversion kits were in 1998.

The 460 Rowland case is approximately 1/16" longer than a conventional 45 ACP. However, the overall cartridge length of the .460 Rowland is the same as the 45 ACP as the bullet is seated a bit deeper, which means case capacity for both is identical. Case length for the ACP is is 0.898" and cartridge overall length is 1.275". Case length for the .460 Rowland is 0.955" and cartridge overall length is 1.275". The purpose of the extended case length is to prevent the high pressure .460 Rowland from being chambered in a standard firearm chambered for the low pressure .45 ACP. The overall cartridge length restriction imposed on both cartridges is established by the cartridge length capacity of the 1911 design.

There are two key elements to the .460 Rowland concept. The first is a sharp increase in cartridge maximum pressure over the .45 ACP and .45 Super. Maximum Average Pressure is: 45 ACP (21,000 PSI), .45 ACP +P (23,000 PSI), .45 Super (28,000 PSI), .460 Rowland (40,000 PSI). The result of this pressure increase is a potential for 185 grain bullets to achieve 1,500 fps MV and 230 grain bullets to achieve 1,340 fps. The second element, in regard to 1911 type autoloaders, is to dampen or reduce the velocity of the slide to a manageable levels.

Any 1911 autoloaders converted for this cartridge require a compensator. The increase in slide velocity over a standard .45 ACP, or even a .45 Super round, cannot be properly controlled with an increase in recoil spring rate alone. A conversion requires a compensator to delay unlocking of the 1911 action until pressure has fallen to more manageable levels. Without a compensator, slide or frame hardware failure would be result.

Modified 1911 type autoloaders theoretically can still fire 45 ACP cartridges, however, head spacing would not be at the case mouth, which is the proper location, the cartridge would be held in position by the gun's extractor. Additionally, a bullet would be unsupported for the 1/16" forward portion of the chamber and the low pressure ACP round would not reliably cycle the firearm. Conversion is easy and it is not permanent, so the owner is free to move between .45 ACP and .460 Rowland with a simple change over.

Some revolvers may be modified for use with the .460 Rowland. The typical models are the Ruger Blackhawk and S&W 25/625 Models that were originally chambered for the .45 ACP.

ources

* [http://www.realguns.com/archives/106.htm The .460 Rowland...Whoa Mama!]
* [http://www.realguns.com/archives/107.htm The .460 Rowland...Whoa Mama! Part 2]
* [http://www.realguns.com/loads/460Rowland.htm .460 Rowland Handload Data]
* [http://www.sixguns.com/tests/tt460r.htm Taffin Tests]
* [http://www.clarkcustomguns.com Clark Custom Guns]