Adding Weapons (and other types of gear, spells) IS Possible
tracker ( Member )
rank: Innocent Bystander
Using the HBS Engineering files: http://steamcommunity.com/sharedfiles/filedetails/?id=161519538
Download them here, if you would like: https://mega.co.nz/#!oFdSGD5D!LJdKLnWDg0-fBzR0t6WGCwUrQyMe5h-gzE5TudAPtck
Copy these folders from /Canada/Data/: abilities, items, modes Paste them into your content pack's data folder
The Sample items will now show up in the editor for you.
Making a Streetline Special is done like this: http://pastebin.com/CFFBZ2ju
Some of the information for rifles, SMGs, etc...you will have to figure out by opening the .item.bytes files in the Seattle/DMS campaigns. I am certainly not an expert in this, yet, but it was mentioned by a bunch of people that they thought gear could not be added to the game and it is nice to see that they can be! We can't change in-game models or icons, yet, but I don't care about that.
Thanks to sheridan_hbs!