Rob in VT, there is absolutely nothing wrong with weighing out charges the way you do, but when I first began muzzleloading, I tested weighed charges vs volume measured charges for accuracy, and found that there was absolutely no difference in grouping ability between the two methods. Testing was done in both .45 and .50 caliber slow-twist rifles at 100 yards range, firing both round balls and Maxi Balls.

Keep yore powder dry!!