goon2goblinFactory-new HK MR556 A4 11″ upper receiver kit, unfired and untouched, still in the HK soft case with all factory inserts and manual. This is the civilian A4 variant of the HK416 lineage, using HK’s proven short-stroke piston system and cold hammer-forged barrel. These uppers are known for running clean, staying consistent under heat, and delivering true duty-grade durability without tuning headaches. Key points that matter: • HK short-stroke piston system — cleaner operation and consistent impulse • Cold hammer-forged HK barrel — excellent barrel life and heat tolerance • Factory HK upper — not a parts build, not a clone • 11″ configuration — compact, balanced, and suppressor-ready Ideal for anyone who wants a factory HK piston upper rather than chasing aftermarket solutions. Condition: New in box / unfired Includes: HK soft case, factory inserts, manual, and all original contents Price: $2,200 cash Trades considered in my favor — trade value $2,500 💳 Payment: Zelle preferred or PayPal G&S and Venmo (buyer covers fee) 🔄 Trades: For trade interests, check out my ISO listing. Trades in my favor only.
🔄 TRADES IN MY FAVOR ONLY KAC, Hodge, LMT, Staccato, Trijicon, Aimpoint, Nightforce, ZCO, Tangent Theta, EOTech, SIG, MAWL, OGL, RAID-XE, DBAL, NVG, premium optics/lasers. Search terms: MR556 MR556A4 HK416 HK piston upper
