I recently did an experiment where I used Redding Dry Neck lube before seating bullets versus not using any lube before seating bullets. The brass was twice fired Lapua brass. Everything else was the same. The cartridges that used Redding Dry Neck lube were higher velocity than the ones without.It's ok to use a dry film lubricant in new necks. Other than moly, it won't change anything over a fired carbon layer, and won't affect MV.
Do not use a wet lube..
Moly does affect MV (lowers it), but this is NOT due to reduced friction. Moly is special in that it cools the charge with it's phase change.
A latent heat of vaporization, that other dry films do not introduce.