sentences:  Therefore, the rounded hammer Colt 1903 Pocket Hammers can help date those pistols at a glance to 1903-1907.Unlike the Sporting Model from which it was derived and the 1902 Military Model, that had milled slide grooves and checkered slides respectively, the 1903 Pocket Hammer featured slide grooves at the rear of the slide.The first pistols featured the milled pattern similar to the 1902 Sporting Models, but Colt transitioned to rear cut slides around the spring of 1905, apparently for all their automatics.