In the position you wear your holster, you cant the rig enough so the drawing hand can EASILY establish a firing grip while the gun is still in the holster. One reason for the "FBI" ~4:00 position was that it worked well with their suit coats. For an automatic worn in that position you may need more or less cant to achieve the goal of 'a firing grip while still on the holster' requisite.
If you need to adjust your grip after or during the draw movement, then you need to move the holster location or adjust the cant to allow a firing grip while the gun is still in the holster.
For many of us, a moderate butt forward cant with an OWB holster at 3:30 to 4:00 accomplishes that provision. Rod