The HK416 (Piston) is less reliable than the AR15 (Direct Impingement), but still better than the AK
The HK416, despite its piston system, failed after two rounds in a mud test due to debris ingress. Direct Impingement AR-15s often perform better in such tests as gas venting helps clear debris. The HK416's design, while robust, can still be susceptible to fouling in extreme conditions.













