It's easy to open up a seater stem. Mike your ogive and select the appropriate size drill bit, chuck the stem carefully in a 3 jaw chuck (if you have a lathe) or vertically in a drill press vise (if you don't) or in an appropriately sized collet (if you have an R8 collet fixture and carefully open up the diameter of the seater stem. You don't need the inside diameter of the stem as large as the ogive outside dimension, 0.20 - 0.50 less is fine.
Insertion pressure isn't that much or should not be if the neck bushings are sized correctly.
I make my own stems from drill rod.
With the multitude of pills and varioujs meplat/ogive dimensions today, it would be almost impossible to ship a die set with the exact stem, there is just too many variations.
The main reason why I like the RCBS GM seater dies (other than the front load feature). Simple matter to pull the stem and machine another, plus, you only need one seater die for just about every caliber. Finally, you can visually see the pill being inserted into the neck. You can obtain various follower bushings (that align the neck for insertion of the pill, from RCBS (or make your own if you have that capability). I don't like to wait so I make them as needed.
Thats how I do it and just a suggestion.
I have the machines so I chuck them in a nose collet on one of the larhes, drill in a tailstock chuck and open them up and/or make another specific pill stem.
My issue, if you will is, I load a lot of different pills from various manufacturers in the same caliber brass. So many that I usually keep that specific stem with the specific pill in a baggie.
In a pinch, you could even open the stem with a cordless drill but you need to secure the stem do it don't get away from you.
