Benjamin Discovery on CO2

While shooting the Disco on HPA I was encouraged to see that it grouped well even as the pressure dropped down to around 1000 psi. I degassed the Disco today and filled it up with CO2 to see if it would shoot as well as I was hoping.
I set up the Chrony and got out a tin of RWS Meisterkugeln 8.2 grain pellets. I was shooting in my basement again, from a bench with the target at 30 feet. It stays around 65 degrees in my basement, not the optimum shooting temp for CO2 but at least it is consistent. The gauge on the rifle showed a pressure of about 800-850 psi. The pressure stayed consistent through almost 60 shots.
I was firing a shot every 15 to 20 seconds, with about a minute break every 10 shots to look at the pressure gauge and write down velocities for each 10 shot string. I mention this because I noticed a drop of about 15 fps on the first shot of each string, then the fps would rise back up and stay fairly even for the next 9 shots. I was expecting the opposite to happen as the rifle had time to warm back up during the break between shot strings.
The shots stabilized after shot #10 at around 690 fps velocity slowly dropped to 670 fps at shot #50.

The change in fps didn't seem to affect the POI. In fact the POI remained damn consistent for all 70 shots. I love CO2! The middle target has over 40 shots into a group the size of a dime, in fact looking at the targets all 70 shots would be covered with a dime. Not bad, and I hope to shrink the groups with a few mods to this rifle.

With the lower fps on CO2 I wouldn't do any shooting beyond about 25 yards but with 3X the number of shots per fill, CO2 is perfect for target shooting and plinking.

It took about 10 shots after filling for the fps to even out, the drop in fps is linear on CO2 unlike HPA. On HPA the fps initially climbs, levels off then starts to fall as the fill is depleted.