As a matter of fact, the rear monopod and other "accessories"/"additions" are pretty much the only interchangeable parts. The Tactical's stock won't accept any other R93 barrels, whereas mine can (i.e. I can take a 270 Win. from an R93 Offroad and slap it onto my stock, change the bolt head and voilà: strange looking deer rifle). On the other hand, I can't take a Tactical 2 barrel and put it on my stock; the mounting points aren't spaced the same as the captive bolts that accept them. On top of that, the Tactical 2 is designed to handle the .338 LM, whereas the LRS2 isn't, which explains the lack of barrel interchangeability (safety).
You are right about the scope mounting: Tactical 2 has a Picatinny rail integrated atop the barrel at a 10 MOA taper, whereas the LRS2 accepts only saddle mounts, so any tapers have to be a custom job (as was my case).
I imagine this cleared things up.
Redman, I had a chance to put an LRS2 and my Tac2 side by side last week. At my suprised, the mounting points are spaced the same on the LRS2 and the Tac2. The difference is inside the receiver, the groove that support the barrel inside the Tac2 is about 3x larger and deeper than the LRS2. In other words, your .308 barrel would not fit in my Tac2 because the diameter at the chamber would be to small, the barrels of the Tac2 are much bigger then the rest of the R93 line