An age old debate that'll float in either direction depending on who's fact's are presented at the time.
I've had the 9, and carried it on duty. In the field, with good shot placement, I wasn't impressed. We had a reasonably decent test bed in all the deer we had to destroy after car accidents. 2 to 4 per day was common, and many of the officers who carried the 9's would regularly complain that it took several rounds to do the job. Sometimes it was quite comical.
We used Winchester Silvertips at the time, after I had tested them against all the other brands available. Federal Hydrashocks were decent, but didn't perform quite as well. Speer Gold Dots were just coming out and friend's of mine with the NY State Police were working with Speer on testing and I was waiting for their results.
Anyhow, as a dept., we had the luxury to carry whatever caliber we personnally chose. Initially, I carried a Ruger Sec. Six, then when the GP100 was first released, I switched to that. As more and more autos were entering our ranks, we changed our training somewhat, and started looking to standardize.
When I decided to carry an auto, I had been in contact with Ruger regarding the pre-released P85. They sent me two for evaluation and they shot superbly. One actually was better than the other, action wise, so after sending both guns back, I made arrangements to purchase the one gun and fit it with adjustible sights. Although somewhat boxxey looking, I loved the gun's fit and feel.
I used to get alot of ribbing from other range instructors....you know "a Ruger !!?????", hohohaha.....that was until I used it to take the first auto match we had.....then they quit .
I loved that gun......until I carried it for two weeks!
After I had shot several deer with it at ranges from a few feet to a few yards, I was sadly dissappointed. Yeah, if you popped them in the head at point blank range, you'd get a similar result, but at moderate distances they just jump up and try to run. Real good heart/lung shots too.
Well, I went back to the magnum for awhile, sadly leaving the P85 in the closet. The road guys with the .45's were reporting absolutely no problems, and loved the new 185gr. Silvertips.
Well, I teetered on getting a .45, then Beretta released the Mod96 in .40S&W, and I was smitten.
I bought it, used it, and was never dissappointed...ever, at all.....
It seemed to cover both area's of capacity and power very well.
Not to ramble on here....but my experiences differ as far as caliber choice, and I'll err on the side of bigger is better, only second to good shot placement.
Our forefathers during WWII apparently made the choice due to positive experiences in the field.....I couldn't argue with that.
Take care,
Bob