Relation of crimp to velocity

I don't know much about thermodynamics, but it seems like a bullet held very tightly might 
have an effect on its velocity, which leads to the question above, the idea being a millisecond or two longer burn time resulting from a tighter crimp.  Izzat so?

all I know that IF you think your powder is not burning completely  IE: dirty, tighten your crimp a little, I don't think crimping to the point of pulling the jacket or the coating off helps at all. In F Class rifle they don't even want to crimp they use a mandrel to achieve 2-3000 of "neck tension" just my 2 cents, novice don't know doo doo.

And Pope just seated the bullet in the rifling and slid the case full of powder in behind it.

Crimp enough to prevent bullet moving recoil

This isn’t rifle but crimp does affect velocity. Light to heavy is about 50 fps. That doesn’t say anything about precision.

38 factory hbwc used to have a cannelure that bites into the skirt for a better pop from increased bullet pull force.

I thought it might have an effect, which is why I thought Atl. arms rounds higher recoil might be due to a stronger crimp as they had 
the same velocity as my handholds and the same wt bullets.

In my limited experience trying different crimps, it makes a difference, but not a lot. I lost the records but from memory I saw a small, statistically significant, increase in velocity going from light (.469-.470") to medium (.467-.468") to heavy (.465-.466") but didn't see a repeatable difference on the target. Maybe if I had shot a whole lot of rounds I would have seen a difference in accuracy. Maybe. I settled on light-medium crimp, enough so that my shortest pieces of brass still got straightened out and haven't changed.

Of course this was one load and one gun a long time ago. Your mileage may vary.