First I have yet to get an R8, but plan on getting one with extra barrels much the same as my T/C Encore and 2 of my shotguns.
As for storing and caring for my extra barrels:
After shooting/using them they get a good cleaning, the same with all my firearms, then my long guns those that I don’t plan on shooting regularly get a light coat of Bore Butter swabed in the bore and on the exterior metal, then placed into silicone socks/sleeves, then placed in a gun case with the designated long gun. For those calibers I plan to shoot regularly the barrel(s) are swaded with a light coat of Bore Butter placed in a silicone sock/sleeve, tagged with the particular long gun info, and placed beside or shelved above the long gun.
I prefer using (Oxyoke now T/C...the yellow) Bore Butter over oils as a preventive for surface rust, and for seasoning new and new to me, firearms when firearms are going to be stored or otherwise not going to the range or getting used for several weeks, or months. This includes, my handguns, being cased with a moisture inhibitor pack.
By light coat, as an example, I mean a good light film, like using a small pat of softened butter to cover a whole slice of toast.
