The standard HK93A2 utilized a fixed stock while the HK93A3 used a retractable stock. The HK93 series had a redesigned semi-automatic trigger pack and metal shelf installed in the trigger group well that made it impossible for it to fit a full-auto trigger pack.
The standard HK93A2 employed a fixed stock, whereas the HK93A3 utilized a folding stock. The HK93 series featured a revamped semi-automatic trigger pack and metal shelf installed in the trigger group well that rendered it incompatible with a full-auto trigger pack.