Update, @DRC458 sent me a write up on the .218 Mashburn. It was developed in OKC by Mashburn arms that some of you old timers may remember.
A.E. Mashburn of Oklahoma City, Oklahoma, designed the .218 Mashburn Bee. In all likelihood it is the most popular of the modified Bees, even though it has the most severe case modification. The Bee case, for all practical purposes, has a 17-grain capacity, and since it matched the 2R Lovell for the same ballistics, loads and performance, and with brass readily available, the 2R Lovell was placed on the back burner while the Mashburn version enjoyed an upward trek on the popularity scale in the 250-yard class of smallbore cartridges.
Like the .22 Hornet and .22 K-Hornet, the .218 Mashburn Bee is easy to form as long as you have a rifle to do it in. Just pop a .218 Bee into a .22 Mashburn Bee chamber, pull the trigger and, voilà, you have a new cartridge. Of all the so-called Bee versions of improved cartridges, the Mashburn moves the shoulder forward quite a bit, but while fireforming over 200 cases, I found that neck and mouth splitting were held to a minimum if the rifle has correct chamber dimensions. I had four that split at the shoulder and two of them had twin splits within close proximity of each other. Annealing in all probability could help, but for only four cases (around 2 percent), I didn’t think it was worth the effort.
