Maybe... Depends on the shop and how old the bucket of weights are. The lead ones are easy to identify but nowadays I think even most shops have switched to non lead for stick on. I got 6 5 gallon buckets last year and some had SOWW that were almost all pure lead, while others were 50%.
For $.20 a pound I'd sort through some and try and see how long it takes to come up with a 5 gallon bucket of lead. The bigger weights are simple to identify. It's the 1/8 ounce, 1/4 ounce and 1/2 ounce WW's that take forever to sort through. Anything larger than 1 ounce is easy to grab, identify and sort.