I’ve checked, M2 AP is legal is most states and somewhat in Canada. Meaning you don’t quite need a 1K single shot 50 cal to drop someone in a LUV or IMV. Also if all you have is an AR-10 with milspec lower and drop in autosear, technically you can extract M2 tips and reload into 308, coupled with bull bore and good scope you practically have a poor person SAW for fire support. But the question being, are there any other legal AP rounds like the M2?