I'm not an expert on Sako but from what I recall from my visits to gunshops over the years is that the L691 in 4 action lengths was a 2 lug action. About 15 years ago a 3-lug sporter version of the TRG-21 sniper rifle was introduced called the TRG-S which was replaced by the three lug 75 about 10 years ago, at the same time as the 2-lug actions were dropped... Now the 75 has been refined and the 85 is available.