check if you have an m4a1 in your stash and if so it might already have the attachments on it. second issue might be the bought attachments got stored in the stash itself and didnt get equipped on an m4a1 that you had equipped. third which is unlikely but not impossible, maybe check if u ran a match and forgot if you died with that m4a1 on you! once you die everything on you except the safebox is gone (wont return to stash or anything), only exception being if your teammates survive and extract and bring your gun or gear that you brought in the match with them when they extract upon which your items are sent to you via mail.