505T and 505A are totally different....The 505T is strong for a mid level ball and rolls great. I sue for fresh house shots. The 505A is for when lanes transition, gets down lane further and angular. I personally didnt care for the the 505A when I threw it, the 505T is a great must have ball
My Current Arsenal:
715T................... 65x4.4x30 1000AB
505T................... 65x4.5x30 2000AB
Bank Pearl...........60x5x40 1500 polished
Dark Star.............70x3.5x40 1500 polished
Red Backlash.......75x3x35 2000 polished