450 Bushmaster headstamps

As far as I know, there are only 5 headstamps for .450 Bushmaster. Federal began loading it this year, but they are using Starline brass so far as I have noticed.

The most recent discovery for me was from a box of Polycase Inceptor frangible ARX, where it has an “INC” headstamp - for Inceptor I suppose.

Matt, Thanks for the info on INC
Interesting Starline did not use the * ^ * headstamp vs the 450 Headstamp, I guess they did not want the words to be to small.

I have a question. When Bushmaster first came out with a .45-caliber short case AR-15 compatible round, it was called the “.45 Bushmaster.” Is the cartridge of that designation the same and interchangeable with the “.450 Bushmaster.”

A matter of filing information for me. If the two are different, pictures of both with case measurements would be appreciated.

John Moss

John, I believe you might be referring to the “.45 Professional,” which was originally developed by wildcatter Tim LeGendre from the .284 Winchester case. The .45 Professional had a case length of 1.771" and was shortened to 1.700" when it became the .450 Bushmaster (apparently at Hornady’s request to work with the 250 grain tipped SST bullet). Hornady also changed the primer pocket to fit a small rifle primer rather than large rifle of the .284 Winchester case.

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.”

John Moss

John, thanks for your explanation. I was not aware that there was a .45 Bushmaster and made the error of a bad assumption. It will be interesting to see if anyone is able to dig up such a cartridge to see how it compares to the others.

Larry, I would disagree with your evaluation that you made an error of assumption. Most of the literature I have seen indicates that the .450 Professional evolved straight into the .450 Bushmaster (Hornady version) and does not even mention the .45 Bushmaster. We are only as good as the literature we use to inform ourselves, especially when the literature is from decent sources.

I still don’t know the whole story about where the .45 Bushmaster comes in, and whether or not it is the same as the .45 Professional or the same as the .450 Bushmaster!

Your input was extremely helpful to me, in digging further into the subject.


John, I appreciate your kind words. I’ve learned a lot from your posts even though our collecting interests don’t often cross paths (I collect mostly rifle with a bit of large caliber ordnance).

Hopefully we’ll learn where the .45 Bushmaster fits in all this!

Interesting on the .45 professional, 350 & 45 Bushmaster, I have nothing in my data may data base or books or magazines , John & Larry, thanks for you input.

AmmoOne - the 350 Bushmaster was a typo on my part, which I corrected on my entry. I do not know of any “.350 Bushmaster” cartridge.

John Moss