Why the cannelure on 9mm bullet?

[KentuckyFisherman]

Federal has a fairly new 9mm 124gr HST bullet in 9mm, but they're available in loaded ammo only. I did find a company named American Reloading that had some of these bullets pulled from factory reject loaded ammo. These may have been loaded for the military because there's a small ring of red something about 1/10th inch above the cannelure. Looks like red lacquer waterproofing to me. A couple of questions:

(1) Since 9mm headspaces on the case mouth you don't crimp the brass when reloading, except to smooth any bell back to straight. So, why the cannelure on these bullets? What's it there for?

(2) Since 9mm bullets are a couple thou smaller in diameter than .38/.357 bullets, could these bullets be loaded into .38 brass, using the cannelure for the crimping? Anyone have experience loading and firing 9mm bullets in a .38 Special?

Thanks in advance for any help. I've reloaded for about 20 years, but mostly rifle calibers. This cannelure on a 9mm bullet really has me puzzled. Here's a photo that's fuzzy, but you can clearly see the red sealant, which is well above the cannelure.

 

[Dusty Stevens]

The cannelure is where they crimp it. You may not realize it but its crimped there and still headspaces there too

 

[Outrider27]

The cannelure is where they crimp it. You may not realize it but its crimped there and still headspaces there too

What Dusty said. If you look at catalogue listings for dies, you will find roll crimp dies and taper crimp dies. Handgun cartridges that headspace on the case mouth are crimped with taper crimp dies, which can be adjusted to give adequate crimp while still allowing proper headspacing of the cartridge in the chamber. They can also be used on jacketed bullets that do not have a crimping groove or a non standard length that puts the case mouth other than over the crimping groove.

 

[243winxb]

A cannelure helps contain the lead core in the jacket on impact.

.355" bullets may be loaded in 38 special brass, but only if the die sizes the case small enough and a 9mm expander is used. Neck tension holds the bullet more then crimp.

Shooting a .355" diameter jacketed bullet in a .358" groove diameter barrel will not produce the best accuracy.

The Ruger 357/9mm convertable revolver , with the extra cylinder fires both cartridges.

 

[KentuckyFisherman]

... They can also be used on jacketed bullets that do not have a crimping groove or a non standard length that puts the case mouth other than over the crimping groove.

Yep, that sounds like what I'm looking at, a round where the cannelure was down inside the case a considerable amount. I guess there might be several reasons you'd need to do that, and that's what I'm curious about.

 

[KentuckyFisherman]

A cannelure helps contain the lead core in the jacket on impact. ...

I was thinking of the cannelure primarily as a place to put your roll crimp when loading for a revolver caliber. I totally forgot it serves other purposes, such as locking the core and jacket together. So, even if the cannelure is seated down inside the 9mm brass, it's still helping the bullet integrity. Thanks, 243.