A Remington going back to the predecessor(s) 722/721/725/600/660/XP-100/XP-100-R/Seven/40X/40XR/700 with-4,5,6,7,A,B,C,D,E,F,G,RR serial numbered receivers....
what has changed?
NOT ALL RR prefix serial numbered receivers are CNC machined in Alabama.
RR prefix serial numbered receivers machined in Ilion,NY will have dot matrix marked-Ilion,NY at 6 o'clock at the front receiver ring/action screw threaded hole.
Any & ALL Remington bolt/handles are TIMED into battery & not for PRIMARY EXTRACTION as are most Custom Clones.
Following your appraised You Tube video producer with what I've coined handle LOCATION(fwd/aft) is only ONE part of the equation & the least important IF TIMED correctly.
Einstein &/or Houdini could not Locate/Time a Rem bolt handle correctly w/o other re-work being accomplished....>FIRST.(& it can not be accomplished w/an oxy-acetylene torch)