Must have a lag switch.
This was previously posted before with the intention to copy classes from other cmr mods, but this tutorial is for creating cmr mods without starting with any cmr mods.

Tutorial to put damage any gun:
1. Go to private match game modes and then select your online vault
2. Turn the lag-switch on
3. Select the gametype in your vault you want to mod
4. Go to private match options and then go to default classes
5. Select any class and then go to the primary weapon and select any shotgun
6. Stay on the proficiency interface of the shotgun and turn the lag-switch off
7. Press ok and then select the damage proficiency
8. What ever gun was in the same default class will now have damage as its proficiency

This method can also be used to other settings of the gametype

Tutorial to make CFT and any other gamemode a 1 point win:

1. Go to private match game modes and then select your online vault
2. Turn the lag-switch on
3. Select the gametype in your vault you want to mod
4. Go to private match game modes and then select S&D
5. Go to private match options and then select score. Leave it on that interface
6. Turn the lag-switch off
7. Press ok and then select 1

Note, the setting that you changed will not say 1 and will say another number, but when you go into the match the score limit will be set to 1. This works with most other settings in the gamemodes.
Also I am posting this because it is another way to do cmr mods with knowing how to authenticate files, resign the files to validate them, and to rehash the file to store it on your device. You are letting the game do it for you.