HI Tb forum

This small thing has been driving me crazy for a long time. How can I change the size of a gun like in this video?
I want to create a pk3 where all of the guns are large.
https://www.youtube.com/watch?v=46wCzOwmTMg

I looked into pak0.pk3/models/weapons2/ > all kind of gun folders here. Each of them has weapon.cfg and .mdc files.
I tried changing the gun size using milkshape program but that program could not save the file as .mdc, only md3. I tried editing and then renaming md3 to mdc.. no use.
Not sure what to do with the weapon.cfg either.

What to do?
Goal = All guns 2-5x the normal size