Larry - LeGendre named his wildcat the .45 Professional, and there is not doubt that the .350 Bushmaster evolved from that cartridge.
That said, I have two items only in a file I titled “.45 Bushmaster.” One is from Scott Logue “Industry News” Feature in the IAQ Journal, Issue 452, Nov/Dec 2006, page 36, where it described the cartridge as follows:
“Busmaster recently announced the release of yet another cartridge designed to be fired from a modified M16/AR15 ;platform. Since Bushmaster is a manufacturer of these rifles one could guess this makes sense. The .45 Busmaster cartridge is basically a rebated rim, elongated 45 Winchester Magnum. Bushmaster has released scant details as of this writing.”
In “Small Arms Review,” Volume 9, Number 12, September 2006, there is an advertisement from Bushmaster Firearms covering a couple of AR-15 type rifles chambered for three different cartridges, all pictured, one of which is described with the name “.45 Bushmaster” in three different spots in the 4-3/4" ad.
A friend just sent me a personal email with an article on the .450 Bushmaster, source of which I cannot read here while typing this, which tells a little different story. It credits Jeff Cooper with the concept of an approximately .44 caliber semi-automatic rifle that was capable of taking big game out to 250 yards. He called this the “Thumper” concept, a term repeat much later in Hornady’s ads for the .450 Bushmaster Cartridge.
The article credited, correctly, Tim LeGendre of LeMag Firearms for the development of his version of the catridge called “.45 Professional.” He is said to have licensed the concept to Bushmaster Firearms International for production and distribution, while Hornady developed the ammunition. Hornady modified the case a little so it would work berrt with its SST Flextip bullet. To quote the article “The name was then changed to .450 Bushmaster, with the blessing of LeGendre, and the cartridge was introduced in 2007.”
So, between Larry, and my other friend, we have an answer with a great deal of information. A great tribute to the guys who work on this forum and the speed with which they answer questions for those of us, like me, that are less informed.
It does beg a new question, however. Now we are faced with three different names for essentially the same cartridge of the “Thumper Concept.” We know that the .450 Bushmaster is 0.071" shorter than the original .45 Professional. The question is, where does the .45 Bushmaster fit into the story? Is it simply a case of Hornady adding a zero to the digits making it .450, or are there actually three different cartridges?
Opinions welcome. Measurements, if known for the advertised .45 Bushmaster cartridge, also welcomed. In fact, the latter might answer the entire question.
Thanks to Larry and my friend who emailed me.
Edited to correct a typo referring to “.350” Bushmaster, which should have said, and now does, “.450 Bushmaster.”