Well Mb03 or TSD R700
 

I wanted to fill the stock with home renovation insulating foam but I'm not sure where to apply. The back buttplate doesn't have any screws and I'm afraid to pull it off. Does anybody know if you can pry it off or apply the foam in the little whole in the front?

If its the same as the VSR and it should be it just comes off. Just pull. Its just a rubber plate with lips on it that fit in a groove.

As far as putting foam in it. Ive never had an issue with rattle or weight for the time Ive had mine.

Just my 0.02

You're looking for this: linky

The butt plate on the stock is damn hard to get off. Any suggestions?

You can try wedging a Philips screwdriver between the stock and the butt plate (careful not to damage the plastic/rubber of either part) to loosen it and the rest is all about elbow grease.

Well, I pried off the back and in the stock is a big weight? with masking tape on it that doesn't want to come out. More help plz. So much helping.

Unless you're unhappy with the balance and/or weight of the rifle, I'd leave it where it is. If you foam the stock without the weight in it, your rifle will be a lot lighter and probably off balance. If you want it to be a little heavier, you can add more weights, but make sure you're happy with the final weight and balance before you foam. The rest should be very clearly outlined in the guide I linked you to a few posts back.

The giant weight blocks the whole stock so I can't foam it b/c theres only a 1cm gap between the weight and the sides.