I am starting to reload for my AR and I was wondering if I need the cannelure on my bullets when I reload, or is the neck tension enough?

No, cannelures are not necessary, I use a Lee crimp die and put a mild crimp on the bullet. After 100's of thousands of round downrange, no problems.

YMMV

Opinions vary on this. Here is what I do. On bullets that have no cannelure I run them into the chamber several time. Then I measure them to see if the bullet either set back or pulled out some.  

So far I am good to go.

Wnen I run them into the chamber I do not baby them. I let the action "fly".

For the most part with good brass neck tension should be sufficient.

No cannelure is fine as long as neck tension is good.

I can only offer my very limited experience but here it is.



Ideally I would only shoot NATO spec ammunition with my ARs. As it is not cheap or easy to find these days these I prefer to get as close as I can. That means a canalure for me when bullet shopping. I would prefer to practice and train with the ammo that most closely resembles my preferred SHTF inventory.



I have not been at it long enough to compare results between NATO and mine but I am working towards that goal.



Anyway, that is where I ended up when I commenced my recent reloading buying frenzy. It sounds as if you were recently bitten by the same bug as me.





P.S.



I finally got a hold of some CCI #41. I am one step closer to my goal of some trial and error comparisons. All I was able to get in the previous few months was Federal primers.

You could always get a neck sizing die like the one from Lee and after FL sizing your brass run it through the neck sizer to get much better neck tension, this is what I do when loading 69 and 77 MK's that I don't want to crimp. Although I don't load these bullets in high volume so its not a big deal to pull the handle one more time to get better neck tension than comes from the FL die after the expander ball opens the neck back up.

I also read were you could FL size with the expander/decapper removed but that would still be two sizing's, one to deprime the brass and one without the expander for tighter neck tension.

It easy for me to decap and FL size with one die, then tumble clean & prep brass, then start on the turret press with neck sizing, then priming (if you want to prime after cleaning and prepping the brass just cut the decapper pin off the neck sizing rod and it wont push the primers back out), then powder die, then seat. (on 4th stage I have a Factory crimp die for all other bullets that I do crimp and don't worry about the neck sizing die)

But even commercial ammo houses can slip up on their process control and lose neck tension.  
Which one of these would you want to shoot in your rifle?:




Cannelures:   Crimp 'em if you got 'em.  It's just another risk management feature to keep murphy away.

iIput a light crimp on bullets for semi's w/o a cannelure with a Lee FCD. It doesn't take much to hold bullets . I have yet to see where a light crimp has any definitive difference in accuracy. A hard crimp on a bullet w/o a cannelure will probably cause some bullet upset that will effect accuracy.

I put a light crimp on every rifle round even thou Dillon says there dies produce enough neck tension