I have also found point blank rounds don't seem to work well at all. I have better success if I stay back a bit. It's part of the game it seems.
I think for M3's the skin is so thin that in RL and AP round will just poke a hole in it, and keep going.
I always use HE on M3's and all they have to do is land close.
What'syoursphincter, enjoy what ever it is you will be doing with your time. I am sure we will not suffer.
bye, bye