I did a quick search for a similar thread, but didn't find one. If i just missed it please link. That being said...
Let's look at a line of guns, the Smith Shields. They can be had in 9mm, .40, .45ACP.
There's something to like about the .45, it's chunky little can of whoop ass. A little short of mag capacity, but big on caliber. But...
.45 ACP was built around 5" barreled guns. The .45 Shield has a 3.3" barrel. And there are a whole slew of 3" 1911 platform guns out there also. If fairly consistently heard that .45 ACP doesn't do well out of shorter barrels. Some testing seems to back it up. It seems to be the same issue similar that .380 has. If you have a hollowpoint that opens up adequately the round underpenetrates. If the round has adequate penetration, there'll be little to no expansion.
Is this true, and if so, for short barrel guns is it better to go with natively higher velocity rounds like 9mm or .40 who's ammo is designed around shorter barrels (4") to begin with?