The vintage cardboard boxes have become collectible, valuable and sought after and therefore the less common ones are selling for a premium in good to excellent condition. I always try and get the most pristine and complete guns I can and that includes the original box, paper work and cleaning kit. there have been several Revolvers I've bought over the years without boxes and accoutrements, and I have since found the correct model and period box for them. While maybe not the original box at least it would have been what the gun came in originally.
I also collect Lionel Electric Trains and for pristine examples of vintage (1930's, 40's and 50's) boxes, the sky's the limit. I have seen pristine empty boxes sell for more than the Locomotives that originally came in them. It was common for Boys to throw away the boxes after they ripped them opened on Christmas morning. While the Lionel Trains easily survived our childhoods, many times the boxes didn't - making them sometimes rare and valuable.
Complete packages are always going to bring more than guns with missing boxes and accoutrements.