Sorry for the length of this post in advance!
Try the 40 Super out of your 45ACP if you want some serious penetration. You'll need a new barrel and spring but man, this round has the goods to be a real knock down, penetrating cartridge.
Here are some stats off Triton's homepage, makers of the 40 Super(www.triton-ammo.com) You can see that only the 44 Mag beats it in muz energy, but not by much. They also make a 165 and 200 gr loads
Cartridge Bullet Wt. Muz Vel Muz Energy Barrel Length
.40 Super 135 gr. 1800 971 5"
.44 Magnum 180 gr. 1610 1035 6"
9 x 23 Win 125 gr. 1450 584 5"
.400 Cor-Bon 135 gr. 1450 630 5"
. 357 Mag 125 gr. 1450 584 4"
10mm 135 gr. 1400 718 5"
.45 Super 165 gr. 1400 718 5"
357 SIG 125 gr. 1350 506 4"
.40 S&W 135 gr. 1325 526 4"
Triton is also coming out with a new cartridge in Jan, will release after it's unvieled at the SHOT show. It will be the 450SMC(small magnum cartridge). It is suppose to only be beat by the 40 Super. This round will use the normal 45 ACP barrel and will only require a stronger spring. Either one of these two should really give you the penetrating, stopping power you're looking for out of your 45 ACp, while alowing you to switch back to conventional 45ACp rounds for practice(cheaper) Here is their press release that I cut off their homepage IRT the 450SMC:
Triton Cartridge News Release
December 5, 2000
Coming in January 2001
The 450 SMC (Short Magnum Cartridge)
For those that want more from their .45 ACP chambered handguns, Triton introduces the new 450 SMC. The 450 SMC is based on a simple principle, to strengthen the weakest link in the .45 ACP chain and boost its performance to new levels. All this while not over-stressing the gun (OEM .45 ACP firearms must be modified with the use of a heavy recoil spring).
To accomplish this Triton went to the heart of the problem, the .45 ACP cartridge case. By borrowing from the .45 Winchester Magnum and .40 Super cartridge cases, Triton has come up with a winning combination. A cartridge case that is internally stronger while maintaining the same exterior dimensions as the .45 ACP.
The 450 SMC combines the robust strength of the .45 Winchester Magnum case with a small primer pocket for the thicker small rifle primer; ensuring the most robust case possible. The small primer additionally provides a visual safety to readily differentiate the 450 SMC from a standard .45 ACP.
The 450 SMC is a great choice for .45 ACP fans offering the flexibility of using both the 450 SMC (with a heavy recoil spring) and .45 ACP from the same barrel. Production firearms for the .450 are available from STI International, 114 Halmar Cove, Georgetown TX 78628, (800) 959-8201.
From the 165 grain JHP at 1,450 fps, to the 230 grain JHP at 1150 fps, the 450 SMC surpasses the 10mm in performance and is second only to the .40 Super.
With its small primer pocket and robust construction, the 450 SMC is the ideal choice for the reloader.
The 450 SMC will be available in our Quik-Shok and Hi-Vel lines.
Quik-Shok 165 grain JHP 1450 fps/770 ft/lbs 5”bbl
Quik-Shok 230 grain JHP 1150 fps/675 ft/lbs 5” bbl
Hi-Vel 165 grain JHP 1450 fps/770 ft/lbs 5” bbl
Hi-Vel 230 grain JHP 1150 fps/675 ft/lbs 5” bbl
For more information, contact David Schmidbauer at 1-800-861-3362