Most new spring piston airguns require a bit of break in time before full accuracy potential is achieved. During this break in, excess lube getting past the piston seal causes the gun to diesel, which isn't good for accuracy. As the excess lube burns off and the piston seal wears in, the erratic dieseling ceases.
Spring piston air rifles are very rough on scopes, and the harsher and more unrefined they are, the harder they are on them. They have a wicked "double snap" or "bi-directiona" recoil upon discharge that can really spell doom to reticles and erector mechanisms.
"Airgun Rated" isn't an automatic promise of longevity. I had a Gamo Shadow 1000 eat up an "airgun rated" and fairly expensive Simmons Pro-Air in about fifty shots. I mounted a Bushnell Sportsman 4-12 A.O. from Wally World to it and that "non rated" scope held up to 15,000+ rounds while I owned the rig and is still going strong.
I use the same scope on my brace of Beeman R-9's. My .177 R-9 is a Goldfinger version that came with a bore-sighted Bushnell Banner. I replaced it with the Wally-World Sportsman because it is clearer, with less internal flare. Both of these have gone over 10,000 rounds without a hitch.
You can't skimp on mounts. I use British SportsMatch or the same thing marketed as the Beeman 5030M and have been using them since they hit the market way back when. On R-Series Beemans, there are milled dimples on the top of the receiver meant for the recoil stop pin on these mounts. This does the same job as a scope stop block. On my Gamo Shadow, which didn't have such dimples, I simply drove the recoil stop pin competely out, and backed the rear ring mount with a Beeman Professional Series scope stop. Zero on that rifle remains rock-solid constant to this day.
As for stock screw torque, I think that 25 inch pounds is about right for Beemans but will have to double-check that. I have no idea what it would be for a Hammerli Nova.
As for wind, the highest ballistic coeffecient you'll find in pellets you can use in a springer is about .032. Most flat-head match pellets will be even worse at .009. With BC's this low, wind IS totally capable of blowing pellets off course significantly. The same breeze that won't phase a .22 LR bullet much will blow a .177 pellet several inches off the mark at 50 yards. So wind correction is part of the fun and challenge of airgunning.
-JP
