Lord only knows how many saboted bullets I have shot through my in line CVA. I have never had one iota of an issue with "plastic" residue. The powder residue shows up first as far as I can tell .... typically 3-4 shots and the fouling becomes restrictive. I do not recall ever seeing any evidence of the sabot's plastic being stripped off by the lands or otherwise ending up as a part of a fouled rifle barrel.
I am certain most "traditional" shooters would roll their eyes at my Savage 10ML .... and smokeless ! You talk about a long range shooting son of a gun! This gun is !
Now as for my old Lyman "Plainsman"? Still my favorite.