I have a couple of 77's, so I have nothing against the actions.
As to why they aren't as popular, I figure it comes down to a few things. It's a heavier action than the rem 700 and takes special tooling to true a 77 on a lathe, where's the 700 is easier to dial in. The rem 700 has the accuracy reputation, so most people will go with what has the reputation. That doesn't mean that rugers aren't accurate nor can accurate rifles be built from them, they just don't have the reputation.
And when we get away from the accuraced M700 style rifle, we go to the more classic blued walnut gun, and that is either an M98 mauser or a pre-64 win mdl 70. That's simply what people want and what they associate with as classic custom rifles.
The other thing that bites ruger is that stupid slanted front screw through the recoil lug. Functionally there is nothing wrong with it, but it is appropriately cursed by stock makers.
