One thing to keep in mind with backpack rifle bags: when carrying backpack-style, the top invariably hits any doorframe you pass under. My experience with my crappy (now unused) Explore case that looks similar to the Savior: hitting the door frames on my house, in the 25, 50, and 100 yd range buildings or stooping down like an idiot and still hitting the door frame only 50% of the time. This really sucks and forces one to “dismount” awkwardly right in the doorway area and sort of defeats the purpose of ease of carry.
This applies to any case of this type, really, country of manufacturer agnostic.
And, if you don’t carry it backpack style, it also defeats the reason for the carrying capacity of the pack (i.e. lots and lots). You murder your shoulder by loading one big case super heavy with all of your stuff and stagger from car to range building like a drunken sailor.
I’ve found that it’s easier to have a slim case for the rifle/ammo/mags slung horizontally over one shoulder while wearing a backpack containing everything else.
One trip, no dismount until I reach the range bench.
My 2¢.
Because I've had that same issue before (mostly with SUV hatchback doors), I put on their 55" case (the longer of the two), and had someone measure the clearance between the top of the bag and a standard interior door jam. I'm 5' 10", and I had roughly 4.5-5" of clearance. The 51" bag you can add probably around 1-2" to that, and likely be at 5.5-6" of clearance.