I use a plain old backpack for range trips so as to keep a low profile. I live in an apartment complex and I don't want to give any hints I have guns.
I rarely take more than 2 guns, and for that I've got a Doskocil foam-lined hardcase for both guns. I also use this case when flying with guns. I can fit that, ammo, and other accessories in my backpack, but it's pretty packed. If I bring one more, the 3rd gun goes in a gun rug. If I bring 4 guns, which is unlikely, I'd probably put them all in gun rugs to save space. Don't think I have enough room in my bag for any more guns than that. But I rarely bring more than 2 guns to the range (not counting the gun(s) I'm carrying on my person). I also don't spend a lot of time at the range, typically an hour at the most.