I'm in a hurry, but you basically save-quit a weapon holder behind a wall, and then you put the weapon on the other side of it. It should "stick" to the wall
Visit this tuturial, (click link) made by my buddy polished lucky, it was very helpful, im not sure if the pictures work or not http://www.forgehub.com/forum/halo-forge-discussion/8924-how-mount-weapons-wall.html
nah, they don't work anymore because that was one of my old photobucket accounts that hit bandwidth limit. I have like 4 accounts lol but just follow the guidelines but it's basically trial and error.
First, find where you want the weapon mounted. Is there any immovable objects nearby close enough to put a weapon holder in? If there are set the object to not spawn at start. Depending on how you want the weapon to stand position the weapon holder next to, below, or above the wall you want it against but be sure that the holder is in an area where an immovable object will be. Then pause the game, save, and quit. Go back into the game and the weapon holder will be wherever you were holding it while saving. It doesn't matter if it is inside an immovable object, because if you put a weapon in it's "holding" range, it will stay, and look like it is sticking to the wall.
Question answered... This needs to be locked now. Just follow the directions within this thread and you should be able to get what you want finished. If this does not help then feel free to ask me or someone who has helped you before.