Like Venko said, Bravo 6 has it in one of their figure sets. Plus, there are plenty of STL files out there that can be 3D printed in 1/35 if someone wants to. OBJ file Stoner 63 rifle・3D printable model to download・Cults
3D stoner 63a lmg model - TurboSquid 1166901
I bet you that there is not much demand for it in the market.