[Darkside]

I was running a 1000 pcs. of 45 ACP brass through the press this morning and noticed some of the BRASS had a canalure near the case mouth. Now I have probable seen this thousands of time but never thought about it.

What the heck is it for?:scrutiny:

Any thoughts.

Darkside

[HSMITH]

It prevents bullet setback in 45 acp. It 'dents' the case in right under the base of the bullet when seated and makes a stop that the bullet will have to overcome before it can be set back in the case. Setback is dangerous, depending on powder used it can cause catastropic pressures. The cannelure prevents setback and the susequent pressure increases.

[Unisaw]

On a related note, does anyone know of an affordable tool to add a cannelure to a case?

[Paul "Fitz" Jones]

I was a C-H distributor in the 70's and last year sold my survival stash of swaging tools and jackets including cannelure tools on E-Bay. I only have a lead wire cut off tool left.

Check with the successor company on the internet. CH4D and they may still make them. Otherwise search for Corbin Swaging tool Company. I still have their interesting 1977 How-To catalog.

Fitz

[Unisaw]

Thanks. I'll check it out.

[Kamicosmos]

I've seen that on .38 and .357 cases as well, and was curious why it was there. Thanks for the valuable info! I thought it was just for design purposes.