Re: PBR & TSR-XP actions
The PBR and TSR-XP actions will fit the same stock inlet, unless there is a tight fit around the trigger, in which case there might be some internal fitting required to fit the larger and more forward MOA trigger of the TSR. Barrel contours remained the same.
To answer the question more broadly, here are the differences in actions:
All three have the same basic receiver, same as the "classic" Winchester M-70 short action: forged steel receiver, flat bottom, integral recoil lug, blade ejector.
The original PBR has the same action, was available in .308 only, came only with the 4 round DBM, three-position stiker mounted safety and had the same basic two-lever trigger of the M-70s, pre-2007. They all had the Controlled Round-Push Feed (CRPF) hybrid bolt with sliding plate extractor and blade ejector.
The PBR-XP (predecessor to the TSR-XP) had the same action, but now added the Controlled Round Feed (CRF) bolt with claw extractor, just like the "classic" M-70s. It retained the two-lever trigger, but was available in .300 WSM (3 round hinged floorplate only) and offered the same 4rd DBM or 5 round hinged floorplate in .308 Win.
The TSR-XP replaced the PBR-XP. Everything basically remained the same as the PBR-XP, but now had the three-lever MOA trigger of the post-2007 Winchester M-70s. TSR-XPs still offered .308 with 4rd DBM, .300 WSM in 3 round hinged floorlplate, and an short "Ultra Short Action" TSR-XP USA in .223 Remington with 6 round hinged floorplate.
All are drilled and tapped for included scope rails, 8x40 screws.
Hope this helps.