That being said, the OP sounds like he is pretty firm on sticking with his Glock .40 for backpack Bowhunts. With that caliber, he would be MUCH better off with a big, wide, heavy Cast Bullet at around 1000fps.
I think it's the OP's preference that has boggled a lot of people's brains on this thread. SU35 says he doesn't want to carry anything bigger than his Glock 40 cal, and that's the limiting factor. Some folks won't accept that and want to change the discussion, others say they're willing to play along. I have one foot in each camp.
On the one foot, I'm of the opinion that he can do any damn thing he pleases, as long as it does no harm to me. On that basis, I opined that he'd best use a 200 gr bullet, either a flatnose cast bullet or an XTP. Something heavy that will really penetrate.
On the other foot: If the
weight/size of the Glock 23 is the OP's primary consideration, well, there's lots of other Glock handguns the same size that have more power than the 40 S&W. These include the 10mm, which would be arguably better choices for shooting bears. Moreover, there's modest-sized revolvers in 357 Magnum, 41 Magnum, 44 Magnum, and 45 Colt that come close to fitting the size/weight bill, and pack a helluva lot more wallop than the 40 S&W.
So the OP's insistence that we have to restrict the discussion to his 40 caliber Glock because of
size/weight doesn't really hold up.
What it seems to come down to is a guy who already has a handgun (perhaps his only handgun?) and he doesn't want to buy or carry another handgun, even though the handgun he's got is marginal for the task. And he wants other folks to endorse his intention of using this marginal caliber handgun by recommending a load that stretches his handgun's performance to the very limit. And that's an endorsement I'm just not comfortable making.
It's a "right-tool-for-the-job" issue, IMHO. I might be real comfortable with my light and handy M1 Carbine, but I'd be a damn fool to pack it along expecting to kill bears or moose with it. I'd be smarter to pack a bear/moose caliber rifle and leave the M1 at home. Similarly, if I'm thinking I'm likely to have to shoot a bear or a moose with a pistola, I'd best be packing a pistola that's proven capable of reliably stopping bears and moose.
I guess that's all I have to say about this thread.
