I can now confirm my bottle is the size of 68Blackbird's after seeing his pic, so I guess that means it's an 80 cfm assuming his comments are correct. Appears my 3 foot guess was about right. Photo of mine is not convenient at the moment.
I also agree that C25 is the gas of choice for MIG welding steel. Argon is incorrect as the CO2 is a very necessary component. Pure Argon is for welding Aluminum, not for steel.
Also agree with Firebird's comments...always close the main valve on the bottle when not in use. You don't want to rely on your regulator holding back 1600 psi or whatever these bottles are in long term storage...I believe most will seep very slowly and undetected.