Have you had your 10mm over a chronograph?Oh I don’t think it’s bad, I shoot 220gr hardcasts out of mine. My titanium 44mag weighs about the same as my G29 and both are not bad to shoot.
I need to find a good hardcast for my G48, I just love the size and feel of that frame. I think the only diff between it and your 43x is a slightly longer barrel or maybe the grip is longer.
I found factory loads to be WAAAAY slower than posted. My personal loads at 1250-1300 for 200's are plenty harsh. I have a 329, 45super, 454, 460xvr for reference.