Has anyone used the Underwood monolithic bullets for hunting? Just browsing through ballistic tests and they seem to do well in gel so just wondering how that translates to real-world results. Looking at the 10mm in particular. I have favored heavy bullets, usually hard cast, but the tests have me wondering how the others perform.

I can't answer your question from first-hand experience, but I saw some good results from those Lehigh bullets on game a few years back online.

In case it's useful, here are some chrono results for them when loaded by UW in 10mm:

YouTube has a bunch of videos, there’s one.

I wonder why they never compare them against hardcast?

Surprisingly similar. Thanks for the link.