[Sturmgewehre]

I've found over the years that generally speaking, any handgun designed initially around a particular caliber will tend to be more reliable in its original chambering. I can't prove this scientifically of course, but I do base this on decades of shooting experience.

Take the XD9 as an example. In my experience the XD9's I've owned over the years would feed anything I put in them. I've had XD45's that were somewhat picky about the ammo they would reliably feed. This was confirmed for me when James Yeager said that he's never had a XD in .45 or .40 complete one of his training courses without at least one failure (usually several). But he confirmed that the XD9 pistol has completed his courses without a failure many times.

The XD started life as the HS2000 and was designed around the 9mm cartridge.

I've had similar experiences with Glock pistols, my 9mms have displayed typical Glock reliability while my .45's have been a bit more fickle.

Conversely, I've found .45 ACP 1911's to be reliable pistols with a wide variety of ammo yet the 9mm 1911's I've owned have been far more ammo sensitive.

Anyway, just some of my observations...