Ok, finally got it to the range, with the Altamont grips on.
Verdict - firstly, I need to learn how to shoot a revolver better, but be that as it may - the Altamonts LOOK pretty, but good lord are they painful with magnums.
I had fired 24 rounds of Remington bulk pack 130gr jacketed 38 Special; by the 2nd cylinder I was able to actually shoot at the part of the target I was aiming for; by the 3rd cylinder at ~25 feet I was able to put it into a nice baseball sized group in DA, which for me is pretty good considering the number of rounds I've fired through a revolver in my lifetime is less than 300. Ideally I'd like to get that same grouping at 25 yards, but baby steps...I'd settle for being able to draw and make hits at the same pace as an autoloader...anyway.
Then I decided to load it with some 125gr Magtech semi-jacketed magnums. Nothing special, plain old blue box cheapo stuff. The photo above was the result after 5 magnum rounds. I re-adjusted my grip so the ledge? was way more centered to the right in the web of my hand, fired the last round of magnum, then another 6 of specials...trigger reach was a little iffy but nothing that I don't think I could train into. Just...yow.
Anyway, I put on the gray industrial waste grips and next time I go to the range, I'll try those out. They don't look pretty but they're probably a lot more comfortable...worst case I'll buy a set of rubber Hogues. Those things could tame a small stick of dynamite.
Edited to add - am I happy with it otherwise? Yeah - you can tell the comp does some work, even with the 38s. Because this gun isn't an old 19 with the cut cone, if I ever get good enough to practice with magnums, I can do so without fear of cracking it in half or breaking it otherwise. The front sight with the night sight isn't exactly the brightest thing, but it's got some nice contrast and it works for what it is. I'm looking forward to getting some more time in with it and learning how to shoot these things better.