Given the velocity of a bullet from a sniper rifle I serious doubt the earth's rotation matters spit...
no, it does not matter...
What you're talking about is called the "coriolis effect".
In artillery, where there's a considerable time lapse between the launch of the projectile and the time it lands, the earth has a chance to move a considerable distance. This must be taken into account in targeting, and the counter to it is not the direction of rifling.
I've never heard of a long range rifleman dealing with it.
If it ain't spinning to the right, it's a leftist gun... That should clear up any questions I think... 
Commenting by HaloScan
