I doubt you'll have enough of a signature to isolate the key from your footage... If it's bright enough you can track something to it and your compositing software might get enough to get a good tracker on it.
What are you keying out or tracking to the BB path?
If you have a high enough res camera you might catch a trace of it. But like k3vx said, it all depends on the color of your projectile and the contrast vs the backdrop it's flying past.
The process is essentially an automated magic wand with a feather on the selection applied to every frame... So ask yourself this: If you are able to take any one still shot from this camera and magic wand select the lens smear that is the flying BB (faster shutter will result in less smear and probably less chance you'll have of tracking or keying, but cleaner keying if it shows up).
My live action keying experience is rather limited. I have done it at work, but most of my compositing skill is in the 2d animation field.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.
Last edited by lurkingknight; January 9th, 2014 at 20:54..