How much time do you have?
BLUF: I never got a Glock 20 (tried three different guns, slow learner) to run reliably with heavy, hardcast, wide meplat loads. Lots of folks who run that combination buy a couple boxes of Buffalo Bore or whatever, shoot one magazine, call it good and carry the rest. Over thousands of such rounds, I ran a 3-4% malfunction rate. With a compromised grip, like one might have while dealing with a wild animal, the gun turns into a giant soup sandwich of failure.
I know carry a GP100 as a woods gun, with 158 grain JSP ammo here in SW Washington, and when we go to places like Montana, with 180 grain hard cast.
I've written about it here on p-f, but my search fu isn't finding the thread. Here's a cliff notes version on the
Hill People Gear forum.
For what it's worth, I think the GP100 in 10mm has merit, if you want an L-frame sized gun that starts with "4." The Smith 610 never made sense for me personally, because if I'm going to carry a N-frame sized gun, I'll just get a .44 Mag and handload to whatever power level I want.
If one wants to run an auto-pistol as a field gun, I would suggest a USP .45, as GJM has used in his thread on the field pistol. It will run .45 Super reliably apparently. I've also heard good reports of the M&P .45. It won't run Super, but frankly I'm not sure how important that is.
I haven't been keeping track of results with the new M&P 10mm.
ETA: My HPG forum post was prompted by
this thread, where a dude had similar experiences with FIVE different Glock 20 pistols.