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Goo Off, you can get it at most Auto supply stores and Freds may have it, best stuff I have used for removing "stickem" stuffhttp://www.goofoffstainremover.com/cleaning/tape-stickiness-residue-and-stains
Orange Peel adhesive remover works great, it's made for removing sticker and tape residue.
The reason there are so many Ruger upgrades is because they're necessary.
Goof Off = naptha in an expensive can. Just buy naptha from the paint/hardware store, should work real well for getting tape goop off.
ill just take the gun off your hands so you do have to look at it