If you’re walking a distance then save yourself some effort with a roller bag.
Just pop to your local discount sports warehouse and look around the other sport sections such as hokey, cricket etc.
Paintball is full of suitable bags for airsoft, but prices are inflated - good quality bags for specific purposes do cost £££ but you don’t need to spend that.
Have a good look at the options in the shop as some bags are customised to the sport but May have inserts that are velcroed in place.
My original giant paintball bag has great sections for boots, pods, guns, goggles, roll out barrel sections etc. But everything was in two velcroed units so it spent half the year assembled and the other half stripped down and became a giant travel & festival bag
You should find a suitable bag with a large main area for guns at around £20-£30, and a better modular bag for £40-£60
If your journey is mostly on pavements etc then pretty much any roller bag will do, but if the off road distance is more than a little then check for chunky wheels.
Make sure there’s a comfy carry handle and ideally back strap options and you’re sorted
Avoid ones that don’t have a hard pull handle as the bag will just bounce and spin along behind you