Hi Gunman!
You're right, scoping airguns can be a challenge. Your pump-up's will work great with any decent centerfire or rimfire scope, they've got minimal recoil. Your springers are another matter, and will need some attention to make them shoot well scoped.
You've got 2 things working against you with a springer. First is the complex, harsh (relatively) 2 stage recoil that finishes long before the pellet leaves the barrel. That causes hold sensitivity in the rifle. Second is the comples, harsh (relatively) 2 stage recoil that destroys "normal" scopes.
First you'll need a good airgun rated scope. Unlike a firearm, the recoil from a springer punches the gun forward instead of rearward at the end of the firing cycle. Firearm scope optics can't deal with this, they're braced for the rearward recoil of a powderburner. So be sure to get a good airgun rated scope. Leapers, Bushnell, many others make'em. Loads of reviews out there.
Second you'll need a good scope mount. Some guns and scopes will work fine with 2 piece rings, but many (especially high powered guns) require one piece mounts. All the mounting surfaces have to be clean, I use alcohol to be sure. Everything gets tightened as much as is reasonable, and locktighted. While you're at it, tighten the stock screws too and locktight them as well.
Third, you're gonna have to work on your hold. Lots said about this too, but in general, springers want to be free to recoil, so we hold them loosely. The non-trigger hand (left for most of us) goes under the forearm, at about the gun's ballance point. Just rest the gun on your open palm, don't grip the forearm. Trigger hand loosely grips the stock, just enough pressure to hold the gun. Stock lightly to teh shoulder (I pull it to the shoulder, then relax). Cheek lightly on the stock. Each contact point should be as close as possible to the same each time, any change will affect the recoil and thus the point of impact. This technique is often referred to as the "artillery hold" as like an artillery piece, we allow free recoil of the weapon on the carriage (us in this case), like a howitzer. Finally, followthru, as the long "lock time" of the springer demands it. Watch your impact thru the scope.
Sounds like alot, but once mastered, the springer will make you a better shot with all your guns. Since you say you group OK with iron sights, perhaps your hold is less consistant with the scope mounted, perhaps the scope is moving, perhaps the scope is damaged.
Well, hope I covered something useful...
For more, Pyramid Air's blog (by BB Pelletier) is helpful in describing this and scoping issues.
J
