Big ammo dimensions?

I am having a hard time learning the various >.50 caliber stuff. Some are called by poundage, some by dimensions only and some by diameter and either the gun it was used in or with only one dimension given and you’re supposed to know the rest. Does anyone have a decently extensive list so that I can tell what I have?

It would be especially helpful to have the case dimensions for the "pound"ers. Thanks.

Different countries used different naming conventions, and sometimes they changed within a country over time, so you are correct, it can be confusing.

Most collectors will refer to large caliber (“artillery” as opposed to “big bore African game calibers” or the like) by the bore diameter of the gun and the overall length of the case (in millimeters) and indication if it is rimmed, semi-rimmed, or rebated at the base.

For example, a WW2 40mm Bofors case would be called “40 x 311mmR” regardless of who made it, and the 40mm Bofors was used by nearly every country in WW2. Sometimes it is referred to a “40mm/L60” indicating it is the 40mm gun with barrel 60 times the bore diameter, to quickly distinguish it from a post-WW2 40mm Bofors gun “40mm/L70” with a barrel length 70 times the bore diameter which uses and entirely different 40 x 365mmR case.

The best reference for this sort of ammunition is Robert Hawkinson’s outstanding “A Guide to the Identification and Research of BIG BORE AMMUNITION 20mm to 80cm” which has three section. The first lists virtually all known cases sorted by ascending case size; the second by country and ascending case size; and the third section is a listing by bore diameter and case length (or if a bag type gun) and the country and gun type which used them. He also lists the rim diameter, and shape of case (straigh,t/tapered/necked) and case material (brass/steel) and if a “fixed” or “separate loading” round.

Price was $110.00, but a bargain for the info it contains, and the price may have changed. I heard that he only has four copies of this book left and anyone interested in this stuff really needs to get one. Contact Robert Hawkinson rcjctg [at]

Otherwise, you are left to research each case by trying to guess the country, and then look up their artillery pieces in the caliber indicated by the markings or the mouth diameter and seeing if you can find something that lists the case length or markings. That is the hard way to research artillery cases!

You could look through the Ammo Data Tables on my website, which focus on HMG upwards calibres:

And for calibres up to 57 mm, there are illustrations of many of them:

Tony Williams has done a great service with both is extensive and constantly updated website, and his books.

Tony’s books are especially valuable to put the development of the guns and ammunition in perspective and context of the different weapons and their intended use (air, sea, land) and their success or failure.

If I did not have Hawkinson’s book, I would go to Tony’s site to start there… and probably spend some time looking at all the other cool info that is interesting but not something I was deliberately looking for.

Thank you John, that’s very kind of you.

Thanks, everyone. I’ll check the sources out.