Author Topic: seating and crimping bullets with two cannelures (Read 650 times)

abj · « **on:** February 17, 2003, 03:43:30 PM »

i just purchased hornady 180gr jhp/xtp bullets , they have two cannelures, or bands for crimping, i have a .357 mag revolver, which i also roll crimp, is there an answer as to why they have two instead of one? does it depend on the type and volume of the powder used, or do you go by the maximum overall length? or does it go by a balance? these are questions i cant find answers to in the books , can anyone help me with this? thank-you in advance. abj

KN · « **Reply #1 on:** February 17, 2003, 03:57:29 PM »

That usually is because the bullet may have a dual aplication. Such as a single shot pistol bullet and also for use in a lever action. It would probably need the shorter OAL to cycle in the lever gun. If you can seat it out at the first groove and still chamber it, give it a try. If its too long then seat it to the second. Another explanation could be to give the bullet less surface area to "drag" down the barrel. Less surface area = less friction = higher velocities. KN

Bullseye · « **Reply #2 on:** February 17, 2003, 05:22:33 PM »

I use the crimp groove that gives me the correct OAL per the book. I guess it would not hurt to seat it longer in a gun like the Contender just as long as it was not touching the lands yet.

ricciardelli · « **Reply #3 on:** February 18, 2003, 01:59:03 AM »

Pick the one that fits...

PaulS · « **Reply #4 on:** February 18, 2003, 07:38:33 PM »

abj,
Hornady has a manual that lists their bullets and the overall length of the cartridge as tested. Unless you plan on running your own tests, under controlled conditions, in your own laboratory, I would recommend that you use the data that they already worked up. Careful, responsible, experimentation is what reloading is all about so begin with responsible practices. Just because "it fits" doesn't mean you should pull the trigger.

PaulS

billmaly · « **Reply #5 on:** February 19, 2003, 08:01:11 AM »

If I recall correctly, crimp on the top cannelure. OAL was within 1/100th. Shot with 12.5 grains 2400, Fed 200 primer. Produced fist sized groups, iron sights at 25 yards and stopped a large doe cold at 40 yards. It's a winner!!