The .218 Mashburn Bee
By Chuck Hawks
This is an old and well known wildcat. Sometime around 1940 A.E. Mashburn "Improved" the commercial .218 Bee cartridge, creating the .218 Mashburn Bee. Like all Improved wildcats, the brass for the .218 Mashburn Bee is created (fire formed) by firing standard .218 cartridges in a rifle with an Improved (reamed out) chamber.
Compared to the original .218 Bee, Mashburn.218 has less body taper, a sharper shoulder, and a shorter neck. All of this increases the powder capacity to allow a claimed 400 fps increase in muzzle velocity (MV)--maximum average pressure (MAP) unknown. Since that is about twice the velocity gain that one would ordinarily expect from an Improved cartridge, old loading data for the .218 Mashburn Bee should be viewed with suspicion. Chronographs were very rare and expensive when the .218 Mashburn Bee was designed, and pressure data generally unobtainable except by the major ammunition manufacturers.
The standard .218 Bee is restricted to a MAP of 40,000 cup as it was designed for and introduced in the Winchester Model 62 lever action rifle. Clearly the Improved Bee must be operating at pressures well beyond that limit to even approach such velocities, and its use should be restricted to modern, strong, bolt action and single shot rifles such as the Ruger No. 1.
The .218 Mashburn Bee accepts standard .224" diameter bullets. It is a rimmed, bottleneck case with a rim diameter of .408", a base diameter of .349", and a shoulder diameter of .340". The case length is 1.34", and the overall cartridge length is 1.75".
Fast burning rifle powders such as IMR 4227 and IMR 4198 are recommended for the .218. According to Parker O. Ackley's data, a 50 grain bullet can be driven to a MV of 3300 fps, which is about 700 fps faster than the standard .218 Bee. If true, this would make the Mashburn Improved cartridge about equal to the much larger .223 Remington. The .223 operates at a MAP of 52,000 cup, so I am afraid to guess at the pressure to which Ackley must have been loading the .218 Mashburn Bee. Suffice to say that I would not recommend such loads for use in a Winchester Model 62 (or any other commercially available) rifle!
Copyright 2005, 2014 by Chuck Hawks. All rights reserved.