For Regular Shooters, CMMG recommends cleaning every 250 rounds if it is any caliber other than 22LR. In the case of 22LR, CMMG recommends cleaning every 125 rounds as 22LR ammo is particularly dirty.
For Non-Regular/Casual Shooters, CMMG recommends cleaning the firearm directly after use and making sure the firearm is dry before storing away. Leaving any kind of cleaning solution or oil/lube can cause the metal to expand (As it is a porous material), which can affect the overall functional reliability of the firearm.