I owned and carried a 10mm for a while {Glock 20} and while the gun was a piece of junk {Glock eventually refunded me/replaced it} the caliber was a good one.

The Greenland Sledge Patrol {Slædepatruljen Sirius} issued them for some years as replacements for their SIG 210's. I corresponded with one of the members of the team for a while and they had generally good performance with them on musk oxen and even shot a couple polar bear. But getting good ammo was very hard as most ammo is loaded down to .40 S&W performance. I put them on the Hornady as they really do not need THAT much ammo but their "powers-that-be" in Copenhagen were inclined to dump the pistols and go toa revolver {not sure which one}. Personally I think that would be a mistake for their conditions as I do not like revolvers in deep cold and in frosty conditions.

I wish SIG would chamber their P250/P320 series pistols in 10mm. Looks like they are going to bring out a P220 in 10mm which should be a good pistol but likely heavy as it will be a steel frame. The Sirius patrol were loking at .45's for a time at least but really, the ammo issue comes into play there, too, as they'd need to get heavy +P+ loads with good bullets to do good work. For pure penetration, the .45 works well with the old Lyman 454190 bullet {cast of wheelweights going 262 grains. This is the old 1800's Army semipointed bullet and it will penetrate well and feeds like chocolate chip cookies thru a Beagle. But little peripheral trauma of course around the bullet hole.

Here's a link to an old post on Glocktalk. I'm 3/4Flap.

http://www.glocktalk.com/forums/showthread.php?t=1322067

Here's my G20 in use on the snareline. Shot the yote in the chest but the FMJ didn't make much of an impression to the yote and I killed it by holding it down and standing on its throat.