Re: Savage. 338 lapua switch barrel
I strongly suggest that you obtain access to both 110 FCP HS models (338 LM and 300 WinMag) and compare the stock cut-out dims, mag well dims, action and bolt dims, and mag dims. Don't assume an easy swap, possibly not a swap at all.
Where's all this "wisdom" coming from? I contacted John Whidden regarding doing a custom mod of his single shot Savage long action V-block to accept the bottom metal/mag - to configure my rifle as a semi-take-down (R&R the barreled action for transport). Sent my brand new 110 FCP HS Precision (in 338 LM) to him for a look see. His response, " Due to drastic differences in shape, we won't be able to install our V Block. The current stock and bottom metal is just too wide at the front around the front action screw."
While you are "only" talking about swapping the barrel and bolt, from the complications John mentioned, I'm not at all sure whether the bolt will fit (same dims???) or whether the mag will work (definitely not the same mag setup since the Savage product page says, regarding the 300 WinMag model, "This model has a flush-fit magazine". I suspect potential "no-go" issues going down from the base 338 LM model or up from the base 300 Win Mag model. Then again, maybe just s "simple" bolt and barrel swap and the 338 LMs will fit the 300 WinMag mags. So, back to the intro suggestion - check them out first hand. [You might also call Savage - and, at the same time, see if they'll sell you a bolt and barrel.]