I always thought that one was supposed to seat the primer to the bottom of the primer pocket, all the way around, without crushing the primer. The easiest way to do this is to use a Lee hand priming tool, seat the primer gently but all the way, by feel, then rotate the case 180 degrees within the tool, and again apply the same pressure that it took to seat the primer. This will occasionally result in slightly further, therefore proper, seating. Usually, it was actually seated correctly even before rotating the case. If using this method results in high primers, something is wrong. That has probably been discussed adequately above. If making alterations or additions to the RCBS tool results in deeper seating, then it seems to me that the primer wasn't being felt into the pocket in the first place. That sounds like a design flaw, or possibly an adjustment flaw.
Some folks measure primed cases for uniform seating depth. IMO, this is a mistake. The only time you want unform seating depth is when the pockets are all identical and the primers are all identical. It's probably too hard, or even impossible, to find out when this is true. Again, the primer should be seated gently but firmly to the bottom of the pocket. This is so that the firing pin will not have its blow cushioned by the process of its seating the primer.
My info, or misinfo, comes from an article in the Rifleman (the NRA publication) in, probably, the mid sixties.
As a lot of you know I have just started reloading rifle ammo "223". I loaded 50 rounds last week and fired 25 rounds with no problems. In fact I was kind of pleased. Well today I found out a lot of the primers are 1000'th high. I still have 25 rounds loaded with high primers. Do you think these will be OK?
