Imperial / Canadian cartridges


I know that the original Imperial cartridges were designed by Aubrey White , a Canadian guy that made also custom rifles in the 1989 - 1993 period.

In COTW is written that NASS now produces some very similar cartridges called “canadian magnum” but other sources say that the two lines of cartridges actually interchange . Is it true?

I know that the original Imperial magnums came in 7 mm , 311" , 338" and .358" ( .360) caliber , but COTW lists the 7 mm , 300 ( and not 311) and 338 Canadian magnums . NASS ( according to COTW) eventually marketed a 375 and a 458 version of the basic case too in 1994 .

What was the real relationship between the original Imperial rounds and NASS with their canadian magnum cartridges?

There is very scarce and contrasting info on the web


No one?


In IAA Journal #430 there is–"History of Imperial Magnum Cartridges"
by Aubrey G. White.


These cartridge cases were made with Winchester buttons in South America .
The first lot came out slightly soft but otherwise was excellent quality.

Aubrey G. White would show up at the Calgary gunshows for a few years with Sako rifles and brass. I misplaced the presure tested loading data in a move.

Note that the .300 has shorter head space -shoulder position than the rest to prevent the .311 cartridge being chambered and fired in the .300.

Now I wish I’d picked up a few more boxes of this brass . I gave the first ones purchased to a friend and had to go back the next day for some more cases for me. He probably still has them-Hmmmm!



So “imperial magnum corporation” later change its name to “NASS” ( the USA imperial address and the NASS address reported on COTW are the same)

Another thing : was White the president of the Imperial magnum corporation?

Thanks , wish I had a sample of each of the cases above !!!


If I knew your e-mail address I would send you a scan of the article.


Dick–Just click on “EMAIL” at the bottom of Pivi’s post for his email.


Ron–I have to start paying more attention to these things. Thanks.