Cannelure

[10mm Witness]

When putting a cannelure on a rifle bullet does this lengthen the bullet or create a bulge on either side of the cannelure or both?

[Hickory]

Both.

But, only in small amounts.
Not worth notice

[PbHurler]

I have measured a diameter difference, around the displaced jacket material right at the cannelure area. I've not ever checked for difference in length.

I have run the cannelured bullet back through the point forming die again to true-up the diameter. You'll (I have) also need to clean up the lead tip if you do this, provided you are dealing with a lead tipped bullet.

As Hickory said; I'm not sure it's worth the notice, but I'm not shooting bench rest with my bullets.

ETA: If I was shooting bench rest; I wouldn't be applying a cannelure anyway.

[IllinoisCoyoteHunter]

I have run my cannelured bullets through a push through sizing die to iron out the bulges

[rolltide]

I just run the cannelured bullets through my firearm. That straightens them out right fast and in a hurry. Unless you are using them for BR matches or something, you can shoot the as is.