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You won't notice the cannelure on the bullet if the mouth of the cartridge case covers it. A lot of the projectiles used for revolvers, as well as for rifle ammunition have cannelures that can be crimped into. If the cannelure is visible outside the mouth of the case, it sort of defeats the purpose of allowing a tighter, stronger crimp.

One of the few guns we have sold over the years was an S&W 325PD with the 2" barrel. Found out REAL quick that aluminum case ammo wasn't a great idea -- it locked up the cylinder before the fifth shot of the cylinder. Reasonably hot 230 grain brass cartridges would even consistently start pulling and you'd notice the difference in the report between the last three shots in the cylinder. It is the only 45ACP gun I ever fired that had recoil I'd call sharp, and the gun simply wasn't pleasant to shoot in addition to having the unfortunate habit of pulling the projectiles from the casings. S&W also makes a 329 scandium frame, titanium cylinder 44 magnum revolver that I can only imagine is a handful requiring cartridges with a very firm crimp into the cannelure.