Heckler Koch MR762 A4 Upper Receiver Kit – 13″ Short Barreled Rifle 7.62mm/.308

The Heckler & Koch MR762 A4 Upper Receiver Kit is the pinnacle of evolution in tactical rifle design, offering unmatched capability and uncompromising durability. This kit allows Mil-Spec 7.62 mm AR-style rifles to be retrofitted with HK’s piston and pusher rod system, which virtually eliminates malfunctions common in direct-impingement gas systems by keeping hot carbon fouling out of the receiver area. The adjustable gas block enables operators to fine-tune performance for both suppressed and unsuppressed use, ensuring reliable function under demanding conditions. This kit includes a complete upper receiver/barrel assembly with forward assist, extended charging handle, and free-floating slimline handguard, as well as a bolt group assembly and HK proprietary buffer and action spring. The MR762 A4 is assembled in the USA using US and German-made components and shares many parts originally developed for the renowned HK416. It functions reliably with various quality 7.62 mm or .308 ammunition, making it a top-tier solution for those who demand performance and reliability above all else. Due to its design, these parts are not compatible with fixed-stock AR/M16-type rifles without Mil-Spec hammers on non-HK lower receivers.