I went with KM head, even though it is a 6.04 it performs just as well as any PDI I have seen. On top of that it has a teflon coating! This means it is slot more consistant in changing weather. The teflon keeps the BB moving. Ask any KM TBB owner about jams. The responce I got was "oh that thing that happens in unlubed stock barrels.". I have not had a single barrel jam with my KM in any of my guns. Rember I live in Ohio so that covers slot of weather extremes(-2f to 105f).
sticks