Lead shot in break barrel rifle.

I want to know if you can use lead shot in a break barrel. I know they probably won't be as accurate. 

Going off the chart for lead shot sizes couldn't you use A BB size shot for a .177 and more importantly a buckshot size 3 for the more expensive .25 bore?

Gamo makes a brand of round ball. If the lead shot sizes are true to the bore of air rifles then theoretically you should be able to use them right?