A 'Primer' on Cartridges

[Tony Williams]

I have put together a basic introduction to cartridge and projectile design and designations in an attempt to answer many common questions. It can be found here: http://www.quarry.nildram.co.uk/Cartridges.htm

Tony Williams: Military gun and ammunition website and Discussion forum

 

[patentnonsense]

Great stuff, thanks!

It's hard to find good materials on ordnanace engineering, and you've got a lot of good info up there.

What are the trade shows for military ordinance? Many are listed in Aviation Week, but I don't know where non-airforce hardware etc. is displayed. (Getting in to see the shows is another question, of course!)

And do you happen to know what journals publish technical articles in this area?

Thanks very much!

 

[TimH]

This will do me alot of good. I'm forever asking questions about diffeent cartridges. Thanks Tony

 

[Jim K]

Hi, Tony,

I hope you don't mind a minor nitpick. You say, "The bullet diameter therefore needs to be in between the diameter of the bore and that of the rifling, so that it is gripped firmly."

In a conventional breech loading rifle, the bullet diameter is the SAME as the groove diameter; the bullet is forced, by the pressure, through the barrel and the rifling lands (bore diameter) are engraved into it.

So using the .30 as an example, and ignoring manufacturing tolerances, the bore diameter is .300, the groove diameter is .308, and the bullet diameter (before firing) is also .308. Hope this helps.

(I used the term "conventional" because there have been rifles and handguns made with very deep rifling to allow some of the powder gas to blow out around the bullet to relieve pressure and allow powerful ammunition to be used in a firearm that otherwise could not handle the pressure, such as a .45 ACP in a blowback pistol. These barrels don't last long due to erosion, but achieve the purpose.)

Jim

 

[Jim Watson]

Jim,

I think what you have noted is not an error but a difference in US and European thinking. The American way is for the bullet to fill the groove diameter. There is a strong European school of thought that favors leaving someplace for the metal displaced by the lands to go. I have seen many accounts of 6.5s in particular having .268" groove diameters for .264" bullets. There was an article in a recent Handloader or Rifle magazine that placed the German adoption of a .323" groove diameter earlier than the introduction of the .323" Spitzer; a setup called the Z bore predating the S bore-bullet combination. They were seeing excess pressure and erosion with .318" J bullets in .318" barrels.

But then there was the European school that favored tight barrels for accuracy and thought it ok to shoot S bullets from J barrels. There were some very undersize Sako barrels in the early days of the .243 Win. A mistake or a theory? The first report I read on the 5.45 mm AK 74 gauged it as a .221 caliber but when the supply of Afghanistan captured ammo gave out it shot .224" bullets just fine.

 

[Tony Williams]

What are the trade shows for military ordinance? Many are listed in Aviation Week, but I don't know where non-airforce hardware etc. is displayed.

Military Technology magazine generally lists them, and has occasional articles on ammunition developments etc. I'm in the UK and managed to get to the DSEi defence systems exhibition in London last September, but it took a bit of effort; such shows are not open to the general public.

Tony Williams: Military gun and ammunition website and discussion
forum

 

[patentnonsense]

_Military Technology_ magazine is $130 a year - is it worth it?
Maybe I should place a small ad, and see if I can get the subscription as a free benefit!

 

[Tony Williams]

I find MT a bit patchy; sometimes there's lots of interesting content, sometimes very little. It is very industry-biased. However, it's the only one I know which does cover modern military developments in a professional way.

Tony Williams: Military gun and ammunition website and discussion
forum