dem4570,
You can use a bathroom scale for checking out your bullet seating pressure. I was going to post a picture of a bullet seating gage I made at work years ago, but someone ran off with my digital camera .....maybe later.
Consistant seating pressure is important when you use loose powder. Some powders are more pressure sensitive than others. I usually seat my projectiles with 50lbs. of pressure.
Something else toconsider, is what are you using to seat your bullets. Are you deforming your projectile with the jag you're using?
I assume that you are using a good solid rest/sandbags and not off the hood of you truck.