[ARCHIVED THREAD] - Cannelure dimensions?

Posted: 6/22/2004 6:21:09 AM EDT

Maybe this should have been posted in the re-loading forum but, I suspect I'll have better luck here.

Anybody have measurements for the depth and width of the cannelures on 68 gr Hornady, 77 Nosler OTM and 77 SMK? Inasmuch as cannelured bullets are pretty hard to come by for most of us I'm thinking about scoring one of those CH thingamajigs and rolling my own. Because:

1: More fragmentation is more better than less fragmentation (within reason).

2: For some inexplicable reason, my test rifle drives the cannelured Horny 68's @ 0.6 MOA but sprays the non-cannelured version all over the county.

Thanks in advance.

SD

Posted: 6/23/2004 12:22:49 PM EDT

[#1]

SD,

I'm going to crosspost the answer you got at TF here in case anyone else searches for it. Just so you know.

Tactical Forums Canneluure answer

Quoted:
I worked for Sierra from the late '70's until they moved from Kali to Mo in 1990. I did setup on the bullet presses.

Here's the deal with cannelures:

If anything, they detract from the accuracy of the bullets, especially rifle bullets. The only rifle bullets that we were canneluring were the 22-55-FMJ and the 30-150-FMJ. These bullets were both made on the same machine, a 60+ year old machine called a Waterbury-Farrell that originally made .303 British bullets during WWII. It was an old, cranky POS that barely ran. The jackets we used for those bullets were very thick and made especially for FMJ style bullets. The jacket walls were about .025-.030" thick.Among other things, this allowed us to cannelure them w/o having to worry about splitting the jacket.

Our regular line of hunting and match rifle bullets use much thinner jackets, they'll generally run around .015" in the area where the cannelure would go. There's two problems with canneluring a bullet with a thin jacket. #1 is that you can't go very deep with the cannelure because it's pretty easy to actually split the copper jacket. #2 is that it's difficult to keep the bullet round when you're applying the cannelure. An out of round bullet will not be an accurate bullet.

We have these issues with pistol bullet cannelures too, but it's easier to work with the larger diameter (.35-.45") bullets.

Cannelure QC is a PITA. We have a tight depth and roundness tolerance and it's fairly easy for this to go out of spec.

So how does all this arcane stuff impact you? Well, if you care about the accuracy of your bullets, I'd think twice about canneluring them, or if you do, make sure you shoot a bunch of groups with them to be sure of what you've got.

Here's the dimensions of the cannelure on our 55gr FMJ bullets, from what I remember from 15 years ago: The thickness (width) of the cannelure is .075". The depth of our cannelure was .220-.221" at the deepest part of the top of the cannelure ridges themselves. This is something you'd have to work on yourself though because again, the FMJ jackets are thicker than the regular hunting/target jackets.

If you want to contact me for further info, email me at blacktalon (AT) operamail (DOT) com

[ARCHIVED THREAD] - Cannelure dimensions?

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[ARCHIVED THREAD] - Cannelure dimensions?

[ARCHIVED THREAD] - Cannelure dimensions?