I can somewhat vouch for iDEBz95.
I've noticed on my friend's copy that the Gravedigger has zero pellet spread when fired almost always resulting in NPC insta-kills before the clump of pellets disappear. Don't know how the Bling SG behaves as he doesn't have the DLC needed for it but I'd assume it's the same as it's practically the same gun.
I've found the issue to be something in the weapons.xtbl and I don't know how to fix it
Maybe your friend may have changed the weapon type to that of a pistol, SMG, or a rifle. IIRC, said weapon types don't support the spread that a shotgun is supposed to have, so it gives no pellet spread and instant kills.
Just checked my Vanilla weapon.xtbl and all of the shotguns are classified as shotguns, so your "Vanilla" file is anything but.
Okay, I just put up 2.7 which changes the class of some shotguns back from pistol. Unfortunately this means that they can no longer be used while driving. Deal with it. I also had to reduce the number of RC gun upgrades to 3 instead of 4 so I could add some more lines to the grave digger upgrades.