One thing to add in potential bugfixing is I -did- have the fighting chance pack. So I had the double barreled shotgun by the time the trainer came out.
If you reached as far as chapter 4 I have a small request if possible, every now and again you come across a small white porcelain figure, if you break this you get a key and then when you go to the sanitarium or whatever where you get upgrades the nurse will lead you back to a area with a large amount of locked vaults, each key found opens one of these so if it would be possible to add these keys to the item options it would be appreciated.
While I currently don't have any keys (So a save wouldn't help, at least not from me.) there is a key in the third chapter near the chained chainsaw creature, in that barn area you can reach a ladder up to to a small attic and then there will be a figurine up there, just shoot it to break it and collect the key.
(There are most likely other figurines earlier in the game, it's very easy to miss smaller key items like these keys or the map fragments.)