Not ladder test but some interesting info on the 52 gn SMKs.
The Army used a Mann devise to test their ammo. For 5.56 its a heavy barrel (the one I got from the CMP is a KART) on a Remington 700 action. To test the devise they use 52 SMK's in Remington cases, pushed by 25 grns of 3031 and get groups between .18 - .20.
I tried that load in my Mann devise and it does seem to work.