C - H cannelure tool
A while back I bought a cannelure rolling tool from C - H Tool and Die Co. Started using it last night on some .458 Barnes 400gr spitzers. Tool is not perfect, but is simple, well made and not too expensive. What I found is that under the pressure of rolling the cannelure, the backing rollers frost up the bullet. The rollers are hardened and they are "as machined". I doubt the bullets were hurt, they were just ugly. I took both rollers off and polished them in the lathe, then buffed them lightly with 700 green chrome compound. Bullets cannelured after the polish now match the original finish.
Why cannelure? I know that a good crimp into a cannelure helps prevent a bullet from crawling forward under heavy recoil, and also helps hold it in place during violent cycling. (military ball ammo is crimped into a cannelure). There are some really powerful revolvers available that could have the cylinder lock up because of a bullet creeping forward and preventing the cylinder from rotating. I wouldn't shoot any load in one of them that didn't have the bullet crimped in.
I have no data to support it, but I also believe that a bullet that is crimped into a cannelure helps make early ignition more consistent on big bore cartridges. That's just opinion, but I believe it to be true.
Most of the bullets I shoot are not crimped and don't need to be. I wouldn't cannelure or crimp a 6mmBR for instance, but a Casull, a big Smith or Ruger, or a big bore rifle are prime candidates in my opinion.
I like the tool. It allows me to roll cannelures exactly where I want them on bullets that don't have them or on some bullets that have them in the wrong place.
Good hunting, Tom
Texas State Rifle Association Life Member
NRA Endowment Life Member
A big fast bullet will beat a little fast bullet every time