What is the cannelure's job?

[AR-Bossman]

I always thought it had to do with crimping, but after reading some youtube comments where some people were shredding a guy for saying that, they said it was used to hold the jacket to the lead core and that it had nothing to do with the crimp or where you should set OAL of a cartridge.

Thoughts?

 

[Galil5.56]

I always thought it had to do with crimping, but after reading some youtube comments where some people were shredding a guy for saying that, they said it was used to hold the jacket to the lead core and that it had nothing to do with the crimp or where you should set OAL of a cartridge.

Thoughts?

It can do both. If it's in a good spot to crimp, super. It can also do exactly as is described, that is lock the jacket to the core. 30-30 type bullets usually have the cannelure in a spot that is a great seating OAL, others not so much. Bonded bullets with a cannelure I would think is mostly for crimping, as the jacket and core will be 'chemically' locked... Maybe a bit more gilding the lilly with the cannelure too?

A bullet I recall that does have a cannelure strictly for helping with core retention, are Federal HST's. FWIW, you can buy a C&H cannelure tool, and make cannelures on bullets and cases to your hearts delight. Good luck.

 

[tightgroup tiger]

I consider it the max depth for seating the bullet if I loading heavy loads, and yes, with those heavy loads that is where I crimp to,
whether someone else likes it or not they can go pound salt...

they said it was used to hold the jacket to the lead core and that it had nothing to do with the crimp or where you should set OAL of a cartridge.

I think Hornady and several other bullet companies would have something to say contrary to that.

I can't think some little cannular would have more impact than a jacket that closes up to and on the nose of the bullet to keep a jacket from separating from the lead core.
I crimp to the cannular to keep the bullet from jumping in the case from recoil.

 

[tightgroup tiger]

Galil5.56,
That wasn't aimed at your post, It was aimed at some youtuber shreading someone for suggesting that.

 

[fxvr5]

https://en.wikipedia.org/wiki/Cannelure

 

[FROGO207]

You do realize that years ago the brass itself sometimes had a cannelure in it to stop the bullet from entering the case further after seating. Some of my 38 SPL brass had two of them, one for SWC bullets and a lower one for WC bullets. These days it is easier to manufacture a case with an internal step instead.

 

[Varminterror]

Provide a crimp-friendly indention? Yup, cannelures do that. Lock the core and jacket together? Yup, they do that too, at least to a moderate degree. Create a weak point in the jacket which may cause fragmentation above the cannelure? Yup. That too.

 

[Bfh_auto]

I thought they were put there to make my hand loads look funny.
In all seriousness, there is a reason YouTube shouldn't be used as a primary source of information. It has its place though.

 

[ReloaderFred]

It depends on where the cannelure is, and what it's applied to. On bullets, it's normally for crimping into, especially for revolver rounds, to keep the bullet from jumping crimp and locking up the cylinder. As someone who has done a lot of bullet swaging, I can say without hesitation that a cannelure is not going to help a jacket stay on a core in a cup and core bullet. Bonding does that, whether by heat or chemically. A deep cannalure can be applied which would help to stop the jacket from peeling at that point, since it would be a weak point in the jacket (a stress crack, so to speak).

I have a CH Cannelure Tool, and a Corbin Cannelure Tool, both of which are used for applying cannelures to cup and core bullets I've swaged.

A cannelure placed on a cartridge case can have several functions. One is to help hold the bullet in place by providing a friction point. It can also be placed at the base of the bullet to keep it from being seated deeper during the transition from the magazine to the chamber. The cannelure can also be used to designate specialty ammunition. Blanks are sometimes cannelured near the base to designate that the brass was used for blank loads after being fired. I've also run across quite a bit of Winchester nickel .38 Special cases that have a single cannelure approximately 1/8" above the extractor groove, with would serve no purpose concerning bullets. My assumption, and it's only that, is that it designated some special loading by Winchester, but I never saw the packaging it came in, so it's just a guess.

Hope this helps.

Fred

 

[FROGO207]

I am of the opinion that everyone that posts on You Tube thinks they are a self made expert. I on the other hand find that the more I learn the more I realize I don't know that much about most topics. Learning keeps you young.

 

[GW Staar]

My cannelure self idetifies as the place where I seat and crimp my bullets

Right, sorta self evident isn't it.....which is what makes me wonder why AR-Bossman would even have to witness such nonsense on You-Tube. But then we live in a screwed up century where we have talking heads that make "headlines" with stuff that 20 years ago would be considered laughable. Still should be. Now we have such on Youtube.

If a bullet manufacturer wants to cannelure (degrade accuracy a measurable amount) just to keep their jackets on.....I'd buy another brand. The acceptable reason in my mind for cannelures is in autos where the actions might yank things around enough to need them and why they are required in Military Contracts.

 

[jmorris]

I can prove that it’s not only to hold a jacket to the core because a cannelure isn’t just used on bullets.

These three cases came from the factory like this.



The 405 Remington comes with two sets, though and you could only crimp into one at a time.

FWIW if you have a cannelure tool, you can put as many as you want where ever you want.

 

[mdi]

Well, I never recommend youtube for anything reloading related to anyone with less reloading experience than I have (started in '69). Perhaps a cannalure will hold a core in place on a jacketed bullet ("Core Lock"?), but it is also located exactly in the correct place for crimping, and I doubt if the bullet designer just threw a cannalure in randomly. Almost every bullet will work quite well and safely when seated to the cannalure and crimped, but of course there are exceptions (I don't remember the exact mold number but there is one 38 Special bullet that when seated/crimped at the crimp groove is too long for 357 cylinders. I have that info out in my shop, somewhere).

 

[CraigC]

Provide a crimp-friendly intention? Yup, cannelures do that. Lock the core and jacket together? Yup, they do that too, at least to a moderate degree. Create a weak point in the jacket which may cause fragmentation above the cannelure? Yup. That too.

What he said. It serves both purposes. Sometimes it does this with one cannelure, sometimes multiples.

The HST is bonded and doesn't need a cannelure to hold it together. The XTP, however, does needs its cannelure to hold the jacket and core together. This 300gr .45 XTP separated because it expanded past the cannelure.

 

[Varminterror]

This 300gr .45 XTP separated because it expanded past the cannelure.

And note how cleanly that XTP folded over the cannelure - it’s a weak spot in the jacket. Not at all saying cannelures are bad, but rather they aren’t 100% upside.

 

[CraigC]

Yep, if you blow it up you can see how the cannelure affected how the jacket folded back. It creased at the top and bottom edges of the cannelure. The HST, on the other hand, textbook.

 

[AR-Bossman]

Lots of good info here guys, thanks for responding.

 

[Bandit67]

Looking in my Hornady catalog, not all of the XTP's have a cannelure. The ones meant for revolvers do have a cannelure. From Hornady's Catalog they say "On revolver bullets, the cannelure helps achieve accurate, consistent crimping" As for the interlock their words regarding the cannelure are "Provides accurate and consistent crimping and also works with Interlock ring to ensure the core and jacket remain locked during expansion". So it seems the answer is both.

 

[Rule3]

Now we can move on to the intricacies of a crimp groove in a lead bullet vs a cannelure on a jacketed bullet.

 

[Riomouse911]

The QWERTY commandos that haunt you tube are a pretty pathetic bunch.

I wouldn’t trust 75% of them with a BB gun, much less a .22LR.

Stay safe!

 

[Galil5.56]

Provide a crimp-friendly intention? Yup, cannelures do that. Lock the core and jacket together? Yup, they do that too, at least to a moderate degree. Create a weak point in the jacket which may cause fragmentation above the cannelure? Yup. That too.

That's a good point, and I'm sure any NVA or VC that survived a 3000 fps + M193 hit, could begrudgingly verify this as fact.

I love studying FMJ bullet dynamics as it relates to being an FMJ, but does not act as one/act as the rules of war folks intended on impact. Has me thinking of MK 7 .303 ammo with a sterilized wooden/aluminum portion added to cause it to yaw violently, of even how the Mujaheddin called the Russian 5.45x39 round's bullet, a "poisoned bullet", due to it's horrific terminal performance... Who knew that a bullet with a heavy rear end, and basically a fully covered hollow forward cavity bullet could do so much damage (sic).

I think a lot of non-shooting folks think a bullet, no matter its size simply passes through a body like an ice-pick all of the time... Movies show this, so it must be true. I remember having Red Stag enter the Bradley gunnery range, and accidentally getting whacked at 1000 yards plus with 25mm training rounds. These stag are about the size of elk, and the 25mm rounds were hollow steel w/o explosive. In a thermal sight watching them get hit, it looked like 5lbs of C4 was strapped to them, and detonated. The hydrostaic shock of this M793 TPT (Target Practice Tracer) was unreal, and the bullet left the barrel at about 3600 fps.