The 12.7mm pistol was also messed up until I installed DeadPool2099's optional "No different sprint animations" esp file, then it appeared normal.
To make this more confusing, the weapons all appear perfectly normal on my laptop and really messed up (as above) on my desktop. Both are using MO2 and I have tried both with NO other mods installed. Both are using the most current version of the game and I've used Steam to verify the integrity of local files.
Admittedly, I have a lot of mods on my desktop computer but even launching the game directly from the Steam link, completely bypassing MO2, the weapons don't function. This is using vanilla ini files too.
SOMETHING on my desktop must be conflicting with these mods but I can't seem to find it. I've even compared the two Fallout 4 and Data folders.
PLEASE put your heads together and let me know what to check. Again, something has to be conflicting but I sure can't find it.