Like Deece said, if you're able to, cutting into the wall, and essentially you're creating a "window" in it.
It's a messy, time consuming job, especially depending on your carpentry skills.
You're framing in a window opening like in an exterior wall. You'd need to build a header for the upper part of the wall. (but, be sure that the wall is a non-load bearing wall) Nail a bottom 2x4 for the lower part of the "window sill." Re-sheetrock it. Now you've got a finished opening. L brackets attached to the R & L sides
Or attach 1x2 trim around pegboard for example. Screw the frame into the opening. Attach the pegboard to the frame you've just installed inside the wall. Hang hooks, then guns. Paint the pegboard natcherly, first.
To display it, build a picture frame type molding around the opening. To cover it up, Hang a large painting over it. There's ways to hinge it, but it's a pain.
Or, build a false wall in front of the display wall.
Or, build a 6" deep shadowbox and mount it on the wall, screwing it into studs from the front side. Hide the screws w/ MDF board, diamond plate, whatever you'd like. Drill into it to mount hooks, brackets, etc.
Your shadowbox has to have a nice frame, and using say, a rollup shade, you could glue a picture onto it, then when you want to show your collection, just pull the string and it rolls up, revealing your collection.
Yeah, I used to be a commercial carpenter... B)
btw, Grimjack, nice handle. I remember having all those comics for a long, long time. Wanted to do a 1/6th Grimjack for years... Always remember that one sword fight scene he had w/ his long time enemy. After fighting viciously for several panels, Grimjack gets in a great slice. The enemy says something typically badguy-ish,mocking Grimjack's ability. To which Grimjack replies: "Oh yeah? Nod..." As the top half of the foe falls off.
Great art and story my Timothy Truman I believe...
-Rex