Some how I had deleted my subscription to the RTR Forum
or I would've answer you earlier. The DW Barrel OD is smaller than both the standard 1" cocker bushings AND the 7/8" (?) Phantom bushings so with both there is significant "wiggle" in the pump.
My go-to has been a stock CCI barrel bored for freak inserts using the stock RTR barrel adaptor. The combination of the detents in the barrel adaptor and the bore-sizers is perfect! You get the shot-to-shot consistency w/o the annoying pump wiggle.