Keep your legs locked out - if you bent em you most likely are not going to put enough stress to the gastro - here is a workout that I currently use which works great...
Standing calf raises 1x6-15 (fail at 6 then include some static holds plus a few negative reps till I reach 15 - ouch!)
Seated calf raises 1x10-15 (same here but not as low in reps)
Donkey calf raises 1x20-30 (high reps here but still to failure )
This workout has produced some insane growth in my calves - currently measure around 19.5 inches...need another inch to match my arms - lol
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