I was involved in field-testing the prototypes for the 110BA a couple years back... to the best of my knowledge that stock is their design.
Thats not to say that it wasn't influenced by or doesn't borrow heavily from other designs... they may have a sub-contractor making or finishing parts for them (like they do with the laminate stocks or sending out the bolt heads to be hardened) but Savage does have a fairly impressive row of large CNC machining centers on site so its hardly beyond their capability. The main chassis design is reminiscent of the PDC stocks that I've seen around on the 'Net. The model I have uses that 'Accu-Wedge' thingy, which works fine but makes life interesting if you ever go to rebarrel or change stocks as it required a non-standard size recoil lug. Personally I ditched the AccuWedge and had a local 'smith mill out enough material to fit a full-sized surface-ground competition recoil lug for a large-shank barrel in there and called it good.
The original design used an MagPul AR stock which was too long and didn't go high enough. After some feedback from the testers they changed to using a Magpul G3 buttstock, and fabricated the coupler to attach it to the rest of the chassis after 3D printing a piece to test the fit - which is why I'm fairly sure they make the chassis themselves.
The tri-rail... is a little silly in my opinion on a gun like this, but hey its tacticool

All in all its a very solid gun, and if you ever get the itch to change the brake out its no big deal (regular 5/8-24 thread). Definitely a hoot to shoot!
Later they came out wit the 110FCP in .338LM, which is more like what I wanted at the time - a more conventional HS stock with a much lighter brake and without the funky tri-rail. Same action, trigger and mags.
YMMV,
Monte