Most gun oil's or cleaning solutions will say if they damage polymer or not. CLP Break Free doesn't harm the polymer but they have another product that does. Make sure you read the label before putting it on the firearm.
Try a light touch of Tetra Lube, it works very well on my M&P 15/22. After breaking in my M&P, I cleaned and oiled up with Tetra Lube and she works 99.99999% error free with CCI Tactical ammo. Bolt cleans up in a snap, over all great on weapons.. Good Luck.