Abstract: Methods and associated structures for translating a syringe stopper though a lubricant free tube, such as an insertion tube, syringe barrel or cartridge tube, during the assembly and/or use of the syringe or auto-injector. The stopper in a non-compressed state includes a proximal end, a plunger rod engaging cavity, and a sealing region having a length spaced from the proximal end by a sealing location length. The sealing region includes at least one rib having at least one microgroove within a polymer barrier, the at least one microgroove having an initial width. By the disclosed methods and structures, a translation force biased towards the outer diameter of the stopper is applied to the stopper using force concentrators. The translation force with force concentrators is sufficient to translate the stopper though the tube in a compressed state with a reduction of increase in the initial width of the at least one microgroove when compared to not using force concentrators.