I HAVE (4) M40A1/M40 BARRELS. ONLY ONE OF THESE BARRELS ARE MARKED 7.62 NATO. THE OTHER 3 ARE NOT MARKED WITH A CALIBER. ALL ARE PARKERIZED AND THE MUZZEL END HAS NO TARGET CROWN. THEY ARE STAMPED ON ONE SIDE WITH A HEART, AND REP. DOES ANYONE HAVE ANY OTHER INFORMATION THAT THEY MIGHT BE...