AR15.Com Archives
 What is a cannelure?
BIG-n  [Member]
10/16/2006 3:37:21 AM
I know, I know, pretty basic questions so please don't flame me. But what is it and why is it sometimes desirable on a bullet?
ar-jedi  [Team Member]
10/16/2006 8:59:08 AM

en.wiktionary.org/wiki/cannelure







ar-jedi

BIG-n  [Member]
10/16/2006 9:01:10 AM
Yeah, but what is the purpose?
ar-jedi  [Team Member]
10/16/2006 9:04:42 AM

Originally Posted By BIG-n:
Yeah, but what is the purpose?


perhaps read the wiki i linked to above?

"cannelure

English

Noun

cannelure (plural cannelures)

1. Ringlike groove in the jacket of a bullet which provides a means of securely crimping the cartridge case to the bullet; analogous to the crimping groove in artillery ammunition."

ar-jedi


ETA
ps:
do you see where the crimp and the cannelure meet on the loaded Q3131 i posted above?
BIG-n  [Member]
10/16/2006 9:10:55 AM
Yes I know it is the crimp and maybe i am totally missing the point, but what is the benefit or disadvantage to it. Why would you want the cannelure or not. Some rounds come with it some don't.

Thanks,
KM598  [Member]
10/16/2006 10:05:03 AM
Correct me if I'm wrong...

I believe it is used in defense bullets to cause the bullet to fragment once it's in the victim and starts to tumble.

It's not usually found in match ammo because it can reduce accuracy.

If I'm not right... somebody let me know. I'm no expert.
SPTiger  [Team Member]
10/16/2006 10:40:01 AM

Originally Posted By BIG-n:
Yes I know it is the crimp and maybe i am totally missing the point, but what is the benefit or disadvantage to it. Why would you want the cannelure or not. Some rounds come with it some don't.

Thanks,


You usually see a cannelure in most bullets used in revolvers like .357 & .44 bullets to provide a groove for the case to be roll crimped. This prevents bullet set-back, i.e. prevents the bullet from getting pushed deeper into the case. EDIT- Actually with revolvers the problem would be bullets coming out instead of getting deeper in the case.

On a rifle bullet it's pretty much the same thing. It provides a place for the case to be pressed into the bullet to prevent set-back. This would be more of an issue with a semi or full auto rifle, I think that's why military ammo has bullets with cannelures. Fragmentation associated with the cannelure may be just a bonus. I don't think the cannelure was put on the bullet to cause or enhance fragmentation, I could be mistaken.

Why do all bullets not have it? I think it may have something to do with the cannelure's affect on accuracy. Not all ammo needs to be crimped. Ammo fired in bolt action rifles have little risk of set-back.
Forest  [Team Member]
10/16/2006 11:55:29 AM

Originally Posted By KM598:
Correct me if I'm wrong...

I believe it is used in defense bullets to cause the bullet to fragment once it's in the victim and starts to tumble.

You're wrong.

It's used to enhance reliability. Cannalured bullets don't have the 'seatback' issue that non cannalured bullets have. If a round is fed wrong the bullet can be pused into the case causing dangerous pressure levels and feeding issues.

Also recoil can cause non-cannalured bullets to move in their case (again causing potential problems).

Cannalured bullets are commonly used on rounds that are used in semi-auto firearms (to prevent setback), firearms that are full auto or heavy recoiling (like big bore/magnum revolvers).


It's not usually found in match ammo because it can reduce accuracy.

That part is true.
thebigruss  [Team Member]
10/16/2006 3:41:25 PM
Isn't cannelure Hillbilly talk for what you take when going fishing?
SPTiger  [Team Member]
10/16/2006 3:54:21 PM

Originally Posted By thebigruss:
Isn't cannelure Hillbilly talk for what you take when going fishing?


Yes, the correct line would be "Han' me that cannelure I'm fixinta go fishin'".
P229SAS  [Member]
10/16/2006 6:43:59 PM
They fish with bullets?
WMHM4  [Team Member]
10/16/2006 8:55:49 PM
I'm going to hi jack but on a related topic,

how can you tell if a primer is crimped?
Thunderbolt882  [Member]
10/16/2006 9:19:52 PM
They not only prevent bullet setback in tubular magazines and feeding in autoloaders but also help build pressure inside the case when fired. Another benefit is securing the core inside the jacket.
IAMLEGEND  [Team Member]
10/16/2006 9:22:40 PM
So is the projectile any more inclined to break apart at the cannelure during fragmentation?
Thunderbolt882  [Member]
10/16/2006 9:23:50 PM

Originally Posted By IAMLEGEND:
So is the projectile any more inclined to break apart at the cannelure during fragmentation?


Sure it can, it makes a weak point in the jacket.
IAMLEGEND  [Team Member]
10/16/2006 9:25:08 PM

Originally Posted By Thunderbolt882:

Originally Posted By IAMLEGEND:
So is the projectile any more inclined to break apart at the cannelure during fragmentation?


Sure it can, it makes a weak point in the jacket.


OK, that had been my understanding regarding fragmentation. I realize it is more of a side effect than an intended purpose but I guess it does so none the less.

Thanks.
Forest  [Team Member]
10/16/2006 9:41:27 PM

Originally Posted By IAMLEGEND:
So is the projectile any more inclined to break apart at the cannelure during fragmentation?

Depends on several factors. It helps with some rounds but not with others.
thebigruss  [Team Member]
10/17/2006 10:13:13 AM

Originally Posted By Thunderbolt882:
They not only prevent bullet setback in tubular magazines and feeding in autoloaders but also help build pressure inside the case when fired. Another benefit is securing the core inside the jacket.




Even if the pressure did increase due to a cannelure, which I'm almost certain it doesn't, then it would certainly be so small as the muzzle velocity would be totally unaffected.

As to "securing the core inside the jacket", you've lost your friggin' mind. I've never heard of an uncannelured bullet jacket separating from it's core. How crappy of a bullet design would that have to be to happen?
bfett  [Member]
10/17/2006 10:55:06 AM

Originally Posted By thebigruss:
[

Even if the pressure did increase due to a cannelure, which I'm almost certain it doesn't, then it would certainly be so small as the muzzle velocity would be totally unaffected.


Not so Much BS just not a complete explaination. First off its not the cannelure that increases the pressure but the heavy crimp allowed by the cannelure. When creating extremely downloaded cartridges for say Cowboy Action Shooting you can sometimes get unburnt powder because the chamber pressure is not high enough to sustain the burn (large case capacity small amounts of powder). You have to put a very tight crimp on the bullet to allow the pressure to build to a point where the powder will fully burn and you can get consistant underpowered rounds.

T
Thunderbolt882  [Member]
10/17/2006 7:15:44 PM

Originally Posted By thebigruss:
As to "securing the core inside the jacket", you've lost your friggin' mind. I've never heard of an uncannelured bullet jacket separating from it's core. How crappy of a bullet design would that have to be to happen?


The cannelure crimps the core inside the jacket by mechanical means other than simple friction. Core separations from jackets occur more often than you seem to think.
The reason why you don't see it more often is because manufacturers do their best to avoid it. This is also why there is a market for bonded bullets.
plarkinjr  [Team Member]
10/18/2006 5:25:21 PM

Originally Posted By IAMLEGEND:

Originally Posted By Thunderbolt882:

Originally Posted By IAMLEGEND:
So is the projectile any more inclined to break apart at the cannelure during fragmentation?


Sure it can, it makes a weak point in the jacket.


OK, that had been my understanding regarding fragmentation. I realize it is more of a side effect than an intended purpose but I guess it does so none the less.

Thanks.


Yeah, and it seems that this side-effect (improved fragmentation) turns out to be as critical if not more critical than the seal at the case.
FALARAK  [Team Member]
10/18/2006 5:39:30 PM

Originally Posted By plarkinjr:
Yeah, and it seems that this side-effect (improved fragmentation) turns out to be as critical if not more critical than the seal at the case.


Nothing is more critical than the ammo to be reliable.

What it does after it leaves your gun is totally second in priority. The crimp and cannelure is to ensure reliable feeding and reduced possibility of setback. That is most critical.
FALARAK  [Team Member]
10/18/2006 5:41:18 PM

Originally Posted By thebigruss:


Even if the pressure did increase due to a cannelure, which I'm almost certain it doesn't, then it would certainly be so small as the muzzle velocity would be totally unaffected.

As to "securing the core inside the jacket", you've lost your friggin' mind. I've never heard of an uncannelured bullet jacket separating from it's core. How crappy of a bullet design would that have to be to happen?


I personally have never read where cannelures have any effect on jacket seperation - but jackects seperate from the core ALL the time - in both bullet styles... in both rifle and handgun ammunition.

plarkinjr  [Team Member]
10/19/2006 4:37:54 PM

Originally Posted By FALARAK:

Originally Posted By plarkinjr:
Yeah, and it seems that this side-effect (improved fragmentation) turns out to be as critical if not more critical than the seal at the case.


Nothing is more critical than the ammo to be reliable.

What it does after it leaves your gun is totally second in priority. The crimp and cannelure is to ensure reliable feeding and reduced possibility of setback. That is most critical.


Nurturing socialist hair-splitter!