You can alter the Guns sim file in S3D and change
The hardest bit is matching the IDs in Guns dat to those in Guns sim so you know what gun you are changing
In the shot below note the ID number ( 0x7ea7c1882d511ef4 ) for the 3inchsingle - top pic - matches the parent ID in the bottom pick when node 40 clicked on - so node 40 is for the 3inchsingle
Click the arrow next to node 40
Click on 41 and in the box on the right you can see reload time
Click on the reload time and a box will open up below allowing you to alter reload
times
Dont forget to save your changes
Always back up your original files