700 prefix serial numbered receivers of A,B,C have hardened/tempered & contoured bolt handles.
D(ISS JLock f/pin shroud),E some scroll embellished/some not the handles were not tempered/hardened 7 not contoured/left rectangle shank to wrist above the knob..
a few F mis-stamped receivers in existence.
G handles to current RR prefix serial number receivers are of "short cam" handle design from 2006 to present when the X Mark trigger groups were introduced.
4,5,6,7,A,B,C,D handles are of "long cam" design & will get the proverbial ding/divot in the cam surface as the handle is .080" out of TIME radially.
E,G,RR handles of 'short cam' design will be .160" out of TIME radially for primary extraction.
S prefix serial numbered receiver have 3 generations from mid 90's to RR's of current production.
TT receiver bolt handles are of lightened/skeletonized in the knob end & underside of the handle shank.