The 10 mm is certainly way more powerful than the 9 mm, but it still does not deliver more power than a .357. Buffalo Bore 180 gr 10 mm ammo delivers slightly less energy than the .357 (728 ft/lbs), so expected results should be identical. The one advantage the 10 mm pistol has, especially the Glock 20, over a .357 revolver, is magazine capacity...
Now do not think that I am bashing the Glock 20. It is actually one of my favorite handguns. I have been owning one for decades (generation 2) and love it, but objectively the 10 mm is not a DG cartridge...
The .44 Mag is a big step forward. It gets us to about 1,100 ft/lbs with 300 gr bullets. Almost double the power of a .357 / 10 mm but still only 25% of the DG minimum...
Again, do not think that I am bashing the 44 mag. My S&W 629 Classic is actually one of my favorite wheel guns. I have been owning it for decades and it has killed a number of deer, and I love it, but objectively the .44 mag is not a DG cartridge...
I do not think that the solution is in higher velocity (.454 Casull; .460 S& W; etc.) although it certainly increases substantially the energy numbers, the same way I do not think that a DG stopping rifle is yearning for lighter bullets at higher velocity...
My own handgun for fly fishing in grizzly territory is the .500 mag S&W loaded with 440 gr hard cast bullets from Cor Bon and delivering 2,580 ft/lbs. That is more than double the .44 mag power. I chose the 4" model because it is easy to carry. The power level is still low by DG-stopping consideration, but 2,580 ft/lbs is not far from what a 30-06 delivers at the muzzle, so it is nothing to be sneezed at, and a .50 cal .440 gr flat nose bullet flying at 1,625 fps delivers quite a bunch of frontal area brunt force trauma...
If you look in the above picture at just the size of the ammo for the three options discussed here (.357/10mm, .44 mag, .500 mag), it is a fairly convincing visual comparison...
Shooting the .500...
My experience shooting the 4" .500 S&W with the 440 gr Cor Bon load is that even with the integrated muzzle break it is about as much handgun has I can handle, and I have rotated the muzzle break 180 degree in order to close the upward vents, otherwise the muzzle blast is such that it gives me a nose bleed after a couple shots. Let me be clear, the muzzle does not hit and bleed my nose under recoil; just the gases vented up through the 3 small vents on each side of the front sight hit me hard enough in the face to give me a nose bleed. Just the gases! I am probably not the only one, and this likely explains why S&W engineered these upward vents to be open or closed by the shooter by rotating the muzzle break 180 degrees.
Shooting with grizzly...
My single experience of actual shooting with grizz is very similar to that shown in the video posted by sandman0921. In my case, the situation was likely much less dangerous and I believe that the encounter was totally accidental. I did not face a female grizz consciously charging to protect her cubs. I was fly fishing the upper reaches of the lower Russian River, below the falls a few hours up stream of the public access on the Sterling Highway. All of a sudden, a young adult grizzly (he was tall but lean) jumped in the river some 20 feet downstream of where I was wadding in the river. He jumped from the very thick growth on the side of the river. I do not think that he even knew I was there, and I think that he was as surprised as I was. I carry the .500 in a belt holster, out of the way when casting, but within instant access. I snap fired one round from the .500 into the water in front of him, and he instantly turned around and fled, just as the sow did in sandman0921's video. I believe that the muzzle blast and concussion alone turned him away...
