Driving band width: How narrow is too narrow?

[Oreo]

I'm thinking about designing an ultra-light boolit for .40s&w. This of course means narrow front and driving bands but how narrow can you go? What types of problems result from going too far?

[runfiverun]

ultralight for punching paper?
i'd compromise the nose before the drive bands.
you could do a 100-110gr button collar boolit and smoke it outta the barell and hold accuracy to 20-25 yds.
i'd keep the drive bands though and go with a thinner lube groove near the rear.
even if it meant you went with 3 drive bands [to reduce some weight] you have to stabilize the thing and spin it.

[Oreo]

I was thinking a kindof high speed water jug / varment style gaping hollow point.

Can you offer any dimensional numbers? Is .070" front & rear bands (equal length lube groove) too narrow? The nose would be a wide tangential ogive so there'd be a little more bearing surface there. I'm thinking 125-135gr.

[runfiverun]

no i think .070 would be fine.
close to the line but should be okay depending on the rifling
that's .140 bearing plus the lube groove.
i'm running @ .180 on some of my rifle boolits,with some nose engraving to help, and i'm not being gentle with them.