The Macdev is suppose to be a Dump chamber type design. James From Macdev and I talked about it as I was helping him setup the Sonic E-Racers.
The Macdev lower end sucks. It is designed to dump the entire valve chamber, and the Cocking rod is suppose to be picked up by the backblock before you leak to much air. To accomplish this they use a Valve stem that is very long and a light valve spring. Their hammer is heavy to compensate for the shorter travel. The hammer moves less than 1/3" before it hits the valve, but moves 1/2" after it has contacted the valve. To get that amount of travel the springs are long and compressed quite a ways, and the hammer itself is long and has a very shallow spring guide/cup in the back of the hammer.
The Macdev lower end is a forced LP system. Not LP because of clean design. They have installed heavier springs in the valve of the Sonic E-Racers to keep up with the Race.
Due to the design, I would recommend a heavier valve spring, average weight hammer with a hole in the front end that would allow the hammer to accelerate enough. Just changing the hammer spring might not work because of the lenght of the Macdev hammer. I normally trim the springs in the Macdev setups I get in here, but I still don't like the result as much as switching hammers. Then sweet spot the gun, looking for about 300 psi.
