Cannelures --- Are they your friend?

Greetings,

I was sent an interesting video of ammo testing.

The use of a cannelure tool was used and the results look interesting...

https://www.youtube.com/watch?v=NzrAgRjYHps

Cheers,

Dave

Like many others, I'd like to see .38SPL wadcutters in the S&W 52-2 optimized for 50 yd accuracy.
From the video, it appears the cannelure is an essential part of that. What I don't understand is that not all commercial ammo makers cannelure their "Target" ammo. Are they not aware of the advantages. or perhaps it's just cheaper to leave off the cannelure?
Looking for cannelure-ing machines!

This doesn’t surprise me at all.  I’ve ofthen said that the Factory Wadcutter accuracy advantage was due to the cannelure in the side of the case at the lower body of the wadcutter.

jwax wrote:Like many others, I'd like to see .38SPL wadcutters in the S&W 52-2 optimized for 50 yd accuracy.
From the video, it appears the cannelure is an essential part of that. What I don't understand is that not all commercial ammo makers cannelure their "Target" ammo. Are they not aware of the advantages. or perhaps it's just cheaper to leave off the cannelure?
Looking for cannelure-ing machines!

Canneluring 1000s of rounds is not a trivial proposition.  This can be automated but these machines would be an additional expense and an additional operation. Margins are thin in the reloading biz.

Great, just what I needed: another project.

That was an interesting video. Thanks for sharing, Dave.

All that testing effort and they only tested at 25yrds.

Good point chiz1180! Looking forward to testing at 50 yds.

Dave, when I saw your post I thought we were talking about bullet cannelures.  So this is off topic.  

I always considered that canneluring a bullet probably deformed it and therefore may detract from accuracy.  But the best 50 yd RR groups I get from my 32acp Pardini are with the Hornady 85XTP.  That bullet has a cannelure and in my gun outshoots the discontinued 60XTP, which had no cannelure.  Interesting.

Dr. Don's point about Hornady putting a cannelure on their XTP85 (and XTP100) 32 bullets is interesting. But, unlike the bullet cannelure position promoted in the video posted by FC60, the XTP cannelure is intended to be located at the mouth of the brass with a (factory roll?) crimp pushing the case edge into the cannelure.

A quick scan of the Hornady website does not display any ammo offered with those XTP bullets, but the closest match are 32 magnum rounds which clearly show the cannelure right at the mouth of the brass.

Most of the advocates of the XTP bullets on this forum, AFAIK, advocate a light taper crimp. Does Hornady know something that we don't?

Federal Gold Medal Match 45ACP 185 button nose jacketed ammo also displays a cannelure on the brass - at a similar position to the video. I bought and used quite a lot of that (very expensive) ammo last year before I got set up to reload. This is a rather subjective opinion, but I did not find it to be particularly accurate in my SARO, and my other 1911 does not like those short stubby bullets. A number of other folks I've talked to have said that the Fed GMM does not work well for them also. These experiences may have nothing to do with the cannelure - but interesting nonetheless.

Wobbley wrote:Canneluring 1000s of rounds is not a trivial proposition.  This can be automated but these machines would be an additional expense and an additional operation.

IIRC, US military contracts for Mk 262 Mod 1 ammo (heavy bullet 5.56 NATO load) specify use of cannlured bullets.  To win a contract to supply bullets, Sierra Bullets developed a "light cannelure" tool to put one into their 77 grainers, having objected to adding one for bullets for the Mk 262 Mod 0 contract.  (Issues noted in the Mod 0 contract were the affect canneluring might have on accuracy, and the cost of doing so.  And now you know why cannelured 77s are available for purchase from time to time.)  Other benefits of cannelures in military ammo include:

• Improved reliability.  "Pull weight" of the bullet increases.  Not only does this affect manufacture (a little more pressure needed to seat bullets), it also affects how well the ammo behaves in use.  Rounds where bullets "set back" into the case drive chamber pressures higher, while bullets (and powder) falling out of cases can fail to feed.  Both conditions will jam a firearm, and;
  
• In rifles, lethality.  Ever wonder why 55 grain loads out of the M-16 are as lethal as they are?  The interaction between a high speed bullet (2500+ FPS at impact) and flesh gets interesting, especially in an area a few inches behind the point of impact.  The stable-in-air bullet is unstable-in-flesh (or any other denser medium), and "keyholes" as a result.  Since the bullet is not designed to fly sideways through a denser medium, it fragments,   With a 55 grain projectile, fragmentation begins at the cannelure, and travels rearwards, the result being a wound channel for the tp, and a large volume of tissue damage due to fragments from the base.  
  

The linked video in this thread noted increased internal pressures in cannelured cartridges.  Black Hills actually puts a crimp on their 77 grain loads, apparently, the increased "pull weight" of the bullet makes the powder (TAC, or a noncommercial variant?) burn cleaner, and improves accuracy.

I should have mentioned that although the 85XTP  is my most accurate bullet/load, I do not "use" the cannelure or crimp into it.  I was only concerned that the process of canneluring the bullet might deform it.  But it apparently does not do much damage because it is quite accurate.