The longer answer is pic rails built to NATO aren't geometrically identical. Hot swapping requires minimizing tolerance stacking. To get something reliable, IMHO 1 piece mount and blue-printed PIC rails.
That would be ideal, but the reality of the situation is that it doesn't matter if each rail is different from one another so long as you mount the scope into the same part of each rail every time.
My Mausingfield's pic rail is the same length as the Nightforce rail I put on my B-14R, so I spaced my rings such that they always attach to the furthest forward and furthest rearward slot on each pic rail. There is no other way for me to attach the scope to the rails, because there's only one position where both rings can be attached to the rail at the same time. I liked the Spuhr mount beforehand because the 1-piece mount gave me confidence, but I was tired of screw heads stripping out and you had to make sure to mount it in exactly the same slot every time or else it would shift your zero a smidge (because different mounting positions will be slightly different).
If you mount the rings or 1-piece mount in the same place every time for each rail, it doesn't matter if the two rails are not identical. The difference between the rails doesn't change over time, it's a measurable constant that's factored into the zero difference between the two rifles. For me that means a small horizontal zero shift when putting the scope on my rimfire rifle, but it's measurable and repeatable because I mount the scope on that rail the same way every single time.
Get yourself a decent pair of scope rings or a decent mount (~$100-200), a decent pic rail for the B-14R (a Nightforce base will cost you $60), and then put whatever scope you like best on top. You'll find that the zero shift between your main rifle and your rimfire is consistent and repeatable, measure it once and then just keep a note on your phone or in your gun case to mark down how big the shift is. Then just change the zero, or dial for the new correct zero, whenever you switch from one gun to the other. My scope is zeroed for 100 yards with my 6 Dasher, and then I just add 0.4 MRAD elevation and 0.3 MRAD of right windage to zero the turrets when I switch to shooting rimfire. Once I move the scope back I take my rimfire zero and subtract 0.4 MRAD elevation and 0.3 MRAD of right windage, and now I'm zeroed for the centerfire gun again.
It's pretty simple and easy, not as complicated as everyone makes it out to be. Get yourself a torque limiter for the ring/mount bases and put the rings/mount in the same place on each rail every time with the same torque - your results will be consistent. Mine have been consistent across multiple rifles and scope/ring/mount combinations, so long as you take the bare minimum amount of care to put the mount/rings in the same spot on the rails each time.