I've had Underwood ammo and still have a little lying around. Quality is very good for sure. There is one thing however that I always point out when I can. I disassembled some of their 10mm rounds (180gr and 155gr Gold Dot) and they use 800x powder. I weighed the charge for each and found both of them to be definitely over "book max" listed by Hodgdon.
What this tells me is, likely Underwoods (10mm at least) is somewhat overpressure. So much so as to be a huge concern? Well he feels safe selling them to the general public so my guess is no they're not so wildly overpressure to be a concern, but they are overpressure.
Glocks and Single Actions