After seeing other fellow shooters with back packs, bags and so on, I went the route of hard boxes.
I have a Plano type large instrument box for ammo, magazines, box of bolts, bipods, scopes, flags, etc -something like this:
https://www.jaycar.co.uk/abs-instrument ... 7/p/HB6385
And I have a Plano shooters box with gun rest with cleaning stuff, Alan keys etc - ideal for cleaning, prepping the guns, etc:
https://www.planostore.com/gun-cleaning ... oters-case
The reason I went this route is that I found that one box will not accommodate all it is needed - unless it is humongous and hard to put in the boot of the car after all rifles have been loaded.
My separate boxes allows me a better management of things and keeps oils and cleaning products away from bolts, ammo and magazines.
The ammo/bolts/mags box can be stored either way as ammo won't ming if goes on its side

The Plano shooters box stores all products upright and has rifle holders.