R. Tillery
"I know it's 'doable', so let's commence with load selection (factory AND homebrewed), range, observations, etc."
This question always gets the nay-sayers going about as quick as when someone asks about using the .357 mag on deer. Well I'm not a nay-sayer as I've killed several deer myself and have observed numerous killed with the .45 ACP. One caveat though, all were out of 5" barreled Gv't Mdls or with my 5.5" Wilson barreled comp gun. Suggest the use of 20-22 lb recoil springs for the heavier loads. A buffer, replaced every so often, isn't a bad idea either.
There are range limitations with any pistol and my personal one was 50 yards with the .45 ACP with iron sights. Yours depends on you and your skill.
The best factory performers were the old Super Vel 180s and the Speer Lawman with 200 gr FAT bullets. A friend has been doing well with the Fed 230 Hydra shocks on blacktails down in the Willamette Valley in Oregon. The original Remington +Ps were poor performers. Don't have any reports on the Corbon or other current factory stuff as mostly reloads are used. I did shoot a large whitetail doe (maybe 200 lbs) years ago on the backside of Fort Campbell, Ky with a WCC 63 hardball once. Range was about 25 or so paces. I say once because she died within 3 steps.
With reloads the heavy hard cast 260 gr Kieth bullets were tried but above 750 fps they really battered the pistols and weren't very good performers on deer. The H&G 68 205 FBSWC over 7.5 gr Unique (usually 1050 fps) did a reasonable job with complete penetration on broadside shots. Best performance was with the Speer 200 gr HP, i.e. the FAT bullet, over the same 7.5 gr of Unique. Velocity was 1025 to 1050 at the muzzle and sufficient at 50 yards to ensure quite reliable expansion, penetration and good terminal ballistics. Those bullets are, unfortunately, discontinued but reports are the 200 gr Gold Dot HPs work as well. I'm sure there are others that work also but those are the ones I know do.
With the exception of the Texas Heart Shot there really isn't that much to penetrate on most deer to get to the vitals (heart/lung). Those 200+ lb monsters are really few and far between in most parts of the country. If you hunt where they are, get a bigger gun. However if you live where the deer run up to 175 lbs or so (and that's not a bad sized deer either) then the .45 ACP in a Gv't Mdl will do if you stay within it's and your limitations, just like we should do with any type of gun we hunt with.
Contrary to popular opinion, little deers are not that hard to kill if you put the bullet where it belongs. You don't really need to use a wrist wrenching mondo magnum throwing humongus amounts of lead to kill them. I have no qualms with those who do like to use guns like that. I used to do it myself. Just learned it wasn't really all that necessary to kill deer is all.
Larry Gibson