Guys,
Possibly a "blonde" question but how different are cartridge drawings compared to chamber reamer drawings? Chamber drawing will obviously have throat lengths/angles etc... included, but at say the case shoulder ... how different are the two measurements if at all?
Cheers...
Con

Chamber reamer drawings, or "chamber prints" show the dimensions of the reamer as specified by the person paying for the reamer if it's a custom reamer.

Otherwise there are industry standards (SAAMI) for both min and max dimensions for both chambers and cartridges. There have to be tolerances in anything machined. The idea is that a max cartridge should fit in a min chamber. Otherwise you couldn't buy a rifle from Winchester and ammunition from Remington and expect them to fit. The differences aren't all that great, measuring only in the thousandths of an inch. They vary from cartridge to cartridge. This wasn't always the case. In the 1800s if you had a Winchester rifle you had probably damn well better have Winchester ammo for it.

You can find the same thing on just about everything you use in daily life from nuts and bolts to toilet seats.

Roy Dunlap's book GUNSMITHING illustrates many min/max dimensions. I'm sure there are other places where that kind of info is available.

Ray

you start with a cart drawing...

send it to the chamber reamer person...
head add a couple thousands here and there, for clearances, so the chamber reamer is always larger than the cart drawing, except the headspace datum

the reloading dies guy takes the reamer print, the cart print, and makes dies that are smaller than the cart print, just slightly, except the headspace datum.

jeffe

Thanks jeffe,
Your comments finally got the light bulb lit up! 'smith has asked for cartridge dimensions to see whether he can grind down an existing reamer for a .411/338WM ... I finally worked out I was indeed having a blonde moment as I was stuck on the dimensions of the neck diameter.
Cheers...
Con