i have just purchased a new Remington R1 and the owners manual says no +P. i have no urge to shoot +P but am curious why some guns will handle it and some wont. it doesnt seem like its a strenght issue as all are pressure tested and approved at much increased pressures. the design of the Rem is no different than most other 1911 and remington has always used very good steel in their guns. please let me know if you have any idea.