I know the USC 45 is a carbine and a carbine to me that uses pistol ammo is more a pistol than a rifle. I have a friend in Germany who went to a HK factory and he was able to watch them make his P30. I told him that I wanted the HK USC in 45acp but the only magazines were 10 rounds. He told me I was wrong and he is sending me 4 30 rd USC 45acp magazines. If they are for real then I'm putting down the 1350.00 for one and when I rebound from that one then I'll get the P30 at a Gun Show. Every gun store owner and store emplyoee tell me that I'm nuts and there is no way to have a 30 round 45acp for the USC. I sure hope I can make the round one day to say I told you so. My friend told me HK makes more than what they have on ther wedsite so I'll have to wait and see. I was going to get another CX which as been a great carbine and fun to shoot steel targets. with but I know deep down the HK has to be better