Thanks! I tried free feeding crumbles but wow, seems any feeder I used there was a lot of wasted feed. I will definitely increase it. I was trying to math it as I read 1/4th cup dry feed per bird and thought I was definitely over feeding them!Feed is traditionally measured by dry weight, not volume. 50 adult birds would be expected to eat about 12# dry weight of feed daily. Depending upon the form of your feed when dry, how much spoace that takes is somewhat "fluid". For me, with the crumbles from the local mill, its about 5-6 plastic folgers coffee tubs worth or roughly half of a 5 gallon bucket's worth - which roughly doubles in volume when I make it a wet mash and it has the chance to absorb all that moisture.
My current flock size is in my sig, below. They free range roughly 5x the space you have, though only two are an improved pasture, the other three are a thinned hardword highland.
How much your pasture saves on your daily feed bill depends a lot on how productive it is in terms of bugs, and in terms of what green its full of.
My advice to you, from my own practice, is that if they finish all their feed in two or three minutes and continue to mob you, they likely need more. If they eat for 8-10 minutes then wander away you are somewhere between the right amount and too much. I take a few of my birds every ten days to two weeks and look inside, use the fat content and overall condition to adjust my feedings of them, in addition to their behaviors. Thru the seasons, my pasture can save between 10% and 35% of my anticipated feed bill.