We use the Caswell guns.
They are a gravity feed which you use all the powder out of the cup unlike the suction style of Eastwood,Craftsman etc.
If you are doing bulk I would suggest getting the adjustable voltage gun at Caswell ,They are $199.00 each and a better made one than the hobby gun.Plus the added power.
Also buy at least 2 guns and several cups.
The down time for color change will slow you with the 1 gun.