albino You're welcome, Al. Karmody said in one of his vids a lot of break barrels come out of the factory w/ defective piston seals. Which affect the velocity and thus the accuracy. Actually, the original SR I received from PA had a defective nitro piston. I had paid for the 10 for $10 test and the tester sent me a SR that was approximately 11% less powerful than it should have been. It didn't affect the accuracy though.
I started a thread about that at GTA. Everyone got involved in the thread and since PA has an account there, the PA execs got involved too. Long story short, the PA tech manager personally tested a SR for me and sent it to me as a replacement. They definitely wanted to ensure I was a satisfied customer. *Smiles*
I had known what a NP2 was capable of thanks to a vid Karmody did on the Benjamin Trail NP2. The replacement SR I was sent had an even higher velocity than the one Karmody tested. It tested out as having 905 fps / 21.6 fpe w/ 11.9 gr .22 Hobby pellets (Karmody's NP2 had 864 fps w/ that pellet). Like I said before, my SR is a superlative air rifle. Now you know why.
There is a downside to using heavier .177 pellets in spring rifles. It wears the spring out faster. Supposedly, the B-19 spring is good for 1500 shots w/ pellets heavier than 9.1 grains. The preferred weight range for a B-19 spring is 6.9 gr-9.1 grs. I don't sweat that too much since (after all) I have 3 Optimus'.
Using 8 grs like you are, the spring should be good for 15,000 shots.
The upside to heavier pellets (at least in my Optimus) is a far better shot cycle. A 7.9 pellet is kinda jolty when fired. The 10.34 gr is smooth. Like it was made for the B-19 spring. Oddly, the 10.5's are a tad too heavy. Velocity w/ 10.34 = 800 fps /14.7 fpe. Velocity w/ 10.5 = 759 fps / 13.4 fpe.
