Thier are alot of factors that come into play with pellets and the gun your using them in! Just to mention a few, first off like RF said and the quality of the pellet used, not all pellets are created equal! RWS SD are a better quality pellet than the CPHP's, I personaly have shot cphp's out of my 89 .22cal and watched them corkscrew out to the target I was shooting at 80yds where as the RWS SD fly straight! This is caused by the way the pellet is made the CPHP's are not balanced as well thats why they corkscrew at long ranges and arnt as accurate as the RWS's and or the BBl just dosen't like the hardness of the CPHP's over the softness of the RWS SD's as said thier are alot of factors that come into play here! Thiers a reason why JSB's & H&N and some of the other pellets cost as much as they do! Cause they work! They are made better with better tooling and better QC, this is why they work out of most AG's really well, remember the ole saying you get what you pay for[ most of the time] Here I'll tell something funny my Chinese rifles wont shoot Chinese pellets, but they'll shoot the expensive German ones and my German rifles shoot the Chinese pellets really well go figure! Just something for you to think about, a softer pellet will comform to the rifling better than a hard pellet will but you don't want it too soft or the air pressure will destroy the skirt of the pellet which effects accuracy!