Does anyone know of a U.S. source for a seating tool that is either handheld or could be fitted to a Lyman press? I am using 5.5 mm primers.

Bob

The Lee Autoprime, with LR punch/tray, works fine for me, with this size primer. At most, you might have to relieve the hole in the tray lug a little.

I've used it with 6.5x55 Swede, and older aussie 7.62 NATO brass, with no problems.