{"product_id":"colt-m4-to-m5-carbine-upper-reciever-kit","title":"Colt M4 to M5 Carbine Upper Reciever Kit","description":"\u003cp\u003e\u003cstrong\u003eReach is wasted if the upper cannot hold zero.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThis kit upgrades a legacy M4 lower with a complete 5.56 NATO upper in 14.5-inch or 16.1-inch chrome-lined heavy barrel, a one-piece M-LOK handguard, and a continuous MIL-STD-1913 top rail.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePerformance Under Pressure\u003c\/strong\u003e: You run the carbine-length direct impingement system, then use the folding iron sights or an optic on the full rail when the distance is not known.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDurability and Reliability\u003c\/strong\u003e: Improved barrel retention, a Colt low-profile pinned gas block, and a 1:7 twist keep the heavy barrel honest under heat and sling load.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFriction Removal\u003c\/strong\u003e: An ambidextrous Radian Raptor charging handle and folding sights arrive with the upper, so the conversion is a mate-up, not a scavenger hunt.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIdentity Signal\u003c\/strong\u003e: A free-float carbine upper on a legacy M4 lower looks like a current working rifle, not a leftover issue gun.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eProof and Credibility\u003c\/strong\u003e: Compatible with Colt M4 and legacy M4 lower receivers. Chambered in 5.56 NATO as a complete upper receiver assembly.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eChoose the barrel length and keep the same rigid upper.\u003c\/strong\u003e\u003c\/p\u003e","brand":"Colt","offers":[{"title":"5.56 Nato 14.5 in. Heavy Barrel Black","offer_id":51719578255675,"sku":"CM556-14H-CK","price":1125.99,"currency_code":"USD","in_stock":false},{"title":"5.56 Nato 16.1 in. Heavy Barrel Black","offer_id":51719578288443,"sku":"CM556-16-CK","price":1125.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0121\/1475\/5646\/files\/1214750_1.jpg?v=1789913128","url":"https:\/\/greatcallathletics.com\/products\/colt-m4-to-m5-carbine-upper-reciever-kit","provider":"Great Call Athletics","version":"1.0","type":"link"}