So I am looking at building a AR-10 from Palmetto State Armory. If there upper and lower states it is chambered in .308 can you fire a 7.62 through it? I know on an AR-15 if you want to shoot 5.56 then the barrel must state 5.56 and you are also able to shoot .223 through it but if it says .223 then it is not rated for 5.56. Is it the same for the AR-10? I emailed their customer service and the guy honestly doesn't sound like he knows what he is talking about. He is saying that if is says .308 then it is also rated for 7.62. If this is true then it is totally opposite from the AR-15 platform. Thanks.