Scott, you recon there may not be enough plenum in that reg'd rig you tried them in? 2000psi seems high enough to get the speed you want. You know how it all works, I was just being nosy
What was much more of interest to me, was the fact that a 2.1 grain increase from the 15.9 to the 18.1 JSBs dropped your MV by a whopping 35 fps. That's a bigger drop in fps than I would have imagined considering an only 2.1 grain increase in weight.