Unless you have a throat length gauge, the way you are doing it sounds OK. I just checked my 300 weatherby the other day the same way. I got a fit so that I could push the bullet in by hand ,then seated the bullet so it was only just being held by about 0.040" ,then seated the case and closed the bolt.(No primer or powder). When I pulled the case out ,the rifling had pushed the bullet in a few mill and there were no marks showing that the bullet had stuck in the rifling and pulled out of the case. At this depth, the bullet was still sticking out too far to eject properly though. With my 308 with a very badly worn barrel, the bullet doesnt contact the lands when just started in the case, I have had to push the bullet into the barrel/chamber with a cleaning rod ,then put another cleaning rod down the barrel from the muzzle end and mark how far it goes until it touches the bullet. Then put a seated round in the chamber (no powder and primer again)and put the cleaning rod down the barrel again and see what the difference is in bullet depth.