Originally Posted by
GJM
I believe the main consideration should be reliability, because if you have a stoppage your pistol is no longer a life saving tool.
Loads that should perform the best, meaning heavy for caliber, wide meplat hard cast, at higher velocity, are the worst for reliability in semi auto service pistols. I have wasted a lot of time and money with different platforms and loads for use as a field pistol, and ultimately settled on the USP FS 45 with Underwood 45 Super loads using the Lehigh xtreme penetrator bullet as a penetrator load, and the Critical Duty +P 45 JHP load for general use. The Lehigh bullet profile feeds well, and I have shot it in many different platforms in 9, 40, 45, 45 Super and 10mm. Wide meplat hard cast loads just have not functioned for me in the Glock 20/29, S&W Gen 3 10mm, and even HK pistols.
If I carried a Glock 20/29 for field use, I would use Hornady factory XTP or Critical Duty as my JHP load, and the Underwood Lehigh load as my penetrator load. Those loads function. Even with aftermarket springs and barrels none of the hard cast loads have functioned reliably for me. Neither has the Federal Trophy Bonded load.
As an aside, for animal defense, I wouldn’t hesitate to carry a 9mm with the Underwood Lehigh penetrator load, ideally backed up with a shotgun with Brenneke slugs.