Ok, this my very first HK pistol so go easy on a novice with a question...how many types of mags were made for the USP full size pistol i.e. different options such as floor plates , different capacity etc. This is my first as said before, a lightly used model (200 rounds through it) but I have my heart set on a P30 and HK45 and maybe a "few" others in the HK line.