FIREARM INFO:

     AR-10: Built by ArmaLite 1950’s, larger caliber.

     AR-15: Colt registered trademark. AR-10 characteristics, smaller caliber.

     M16: Rifle version, military modified AR-15.

     M4: Carbine version, military modified, all upper options, collapse stock

     A-1: Flat top upper.

     A-2: M16, upper with carry handle

     A-3: M16 rifle, upper with/out carry handle

     A-4: M16 “style” rifle, upper with removable carry, adjustable stock.

     10-12 inch: Carbine barrel

     14-16 inch: Mid-barrel

     20+ inch: Rifle-barrel

     Impingement: Original system, gas to bolt carrier.

    Gas piston: Gas to operating cylinder/piston driving bolt carrier.

FIREARM INFO:

 AR-10: Built by ArmaLite 1950’s, larger caliber.

 AR-15: Colt registered trademark. AR-10 characteristics, smaller caliber.

 M16: Rifle version, military modified AR-15.

 M4: Carbine version, military modified, all upper optioons, collapse stock

 A-1: Flat top upper.

 A-2: M16, upper with carry handle

 A-3: M16 rifle, upper with/out carry handle

 A-4: M16 “style” rifle, upper with removable carry, adjustable stock.

 10-12 inch: Carbine barrel

 14-16 inch: Mid-barrel

 20+ inch: Rifle-barrel

 Impingement: Original system, gas to bolt carrier.

 Gas piston: Gas to operating cylinder/piston driving bolt carrier.