A new beta branch of CS:GO, version 184.108.40.206rc, addresses jumping accuracy rates across all weapons.
Jumping inaccuracy has been a long standing problem in CSGO. Certain weapons seemed to offer very easy kills when used while jumping.
After addressing critical and competitive-gameplay bugs related to hitboxes and Smoke greandes, Valve have now turned their attention to this issue and detailed a new system which calculates jumping accuracy that is tied to mid-air velocity.
This update can be read in their latest update ( air time)