if you number the pins anticlockwise from the top, pin one and its opposite are closest to the outer lock edge, furthest away from each other, then pins two and its opposite, then three and its opposite move further in from the lock edge and closer together, pin 4 doesn't have an opposite pin, but is furthest away from the lock edge, there is nut a lot of difference from one pin to the next, but it is there, if you look at pins 1 and 4 and their relative distances in from the lock edge, it is more obvious.
http://imgur.com/JjzGdbK
