Sometimes some ground models look weird because of the rotation Angle. And should be rotated in a certain direction to solve this problem, at least this should be configurable.
Also includes coordinate values.

Some models are stored differently than vanilla. I can't modify the json files to fix the problem.

As shown in the picture, machine guns should not be like this.

I am using 1.20.1 forge.

Sorry, but that is how it is. You can disable the advanced rendering for these items. Unfortunately there is no other solution possible at the moment.