As promised I did a redo of my Original Chronograph Test for my Pedersoli Derringer Guardian #11 4.5mm .177 Pellet Pistol. The first time around I just could not get my Chronograph to read in the poor lighting I had going on that day. I spent a fair bit of time doing some testing with my Chronograph since it is that time of year when the lighting is poor and determined that I need to use the white defusing panels as it seems that my roofline and the low light are playing havoc with the Chronograph readings.
Once I sorted this all out my Chronograph worked perfectly and I was able to get some readings for you with my Pedersoli Derringer Guardian #11 4.5mm .177 Pellet Pistol. As I assumed I did not get much over 350 fps. I also got a lot of variation in the fps, most likely due to the fact that I had to roll down the pellets a bit on the backside in order to feed them in the barrel from front to back, some pellets where tight and some where a bit looser, the looser ones seemed to shoot a bit faster as less of the pressure may have escaped out the back where the primer was situated.