More rounds than you will probably ever shoot. 30,000 + There are also other methods to clean them without sending them out. They do create additional blowback on an ar but the amount of blowback depends on the ar , ammo, can, etc. Generally you wont run into cycling problems unless you are using subsonics or have modified your setup with different buffer weights, springs, etc I plan on adding 2-3 more cans to the collection by the end of summer