I have run my PX4 extremely dirty. 200 rounds of filthy, corroded, ~10 year old ammo followed by 200-250 of modern ammo. When I cleaned it, it took a LOT of time to get all the grime out. It never hiccuped. In nearly 2k rounds, it never has.
Beretta PX4 .40 S&W - Beretta 92FS 9x19 Para - Rock Island Armory GI 1911 .45 ACP - Colt 1968 Detective Special .38 Spc. - Ruger LCP .380 ACP - Daniel Defense M4V1 Carbine 5.56x45 - Ruger 10/22 .22LR - Remington 870 Express Tactical 12GA - 1943 Izhevsk Mosin-Nagant M91/30 7.62x54R