You shouldn't have any problems with the installation and you wont be compromising your stock in any way. As for some sort of filling inside the stock it is most likely hollow with possibly a section for high density foam inserted as filler or possibly nothing at all.animalspooker said:So how can you find out what stocks these cheek rests will work on? I have a Rem 700P LTR. It has a smaller than standard HS stock. Will the Karsten still fit on it and is this HS filled with foam like other stocks. I guess my bottom line question is will a Karsten rest fit on it and will I be able to install it as easily as it appears to be on other stocks?