Other Pre Charged Pneumatic PCP Air Rifles

I've an Air Arms S410 Classic PCP in .22. It's lovely.

Don't worry about the calibre - nobody, and I mean nobody, can agree on the 'best' calibre. .177 flies flatter, making it easier to shoot at range, but hits softer at longer ranges and carries a real risk of overpenetration at shorter ranges; .22 flies like a banana, making it harder to shoot at range, but hits harder at longer ranges and is less likely to overpenetrate at short ranges. There's an old saying, .177 for feathers and .22 for fur, but it's just a saying - you can hunt any legal pest quarry with either calibre just fine.

As you're likely to be ratting at short ranges, watch for overpenetration: if you're at 10m or under, use a decent hollow-point pellet or even a target-style wad-cutter. As AR suggested, at extreme short ranges - 5m or under - you *can* load a pellet backwards to completely eliminate the risk of overpenetration, but be warned that accuracy goes out-the-window.

Obviously, make sure you know about the legalities so you don't get in trouble. You say you've got a springer, so you should already know all this, but for the peanut gallery: it's a legal requirement to keep the gun locked up when not in use, to prevent an under-18 from making off with it, and a trigger lock is not enough as it has to be secured against theft (as does your springer); pick up a chronoscope so you can check the power of both your rifles, as anything over 12ft/lbs will need tweaking unless you want to spend a few years pleasuring Her Majesty for possession of an unlicensed Section 1 firearm; make sure you can hit a target the size of a 20p piece at your chosen hunting range before attempting to take live quarry; be sure of your target and what lies beyond it; do not fire the weapon in such a way that the pellets are at any risk of leaving the boundaries of the property on which you have permission to shoot.

You also need to be aware of the laws on hunting with air weapons. It's illegal to use a sub-12ft/lbs rifle for 'hunting,' y'see, but legal to use it for pest control on a selection of species - including rats. However, it's only legal if you've already tried some other way of getting rid of the pests, and they are an immediate threat to health or livelihood. In the case of rats, if you've tried poison and trapping without success, you're covered - but don't turn to the rifle as a first resort, or PC Plod may have questions to ask.

Also, don't store your rifles in a gun slip or padded case; they'll rust. Either buy a silicone-treated gun sock or secure them in a cabinet where they can breathe, and remember to wipe 'em down with an oily rag or silicone cloth after each handling if you want to avoid rusting.

EDIT: Oh, and pick your scope carefully. Assuming you don't want to splurge for night-vision, remember that you'll be hunting rats mostly in dim light: pick a scope with a large objective lens (50mm for preference, 60mm would be great) and with a low minimum magnification (4x at the most, 3x if you can get it.) If you can't afford a scope with parallax correction, you'll need to manually re-parallax: most scopes are set for 100 yards, which will be useless on an air rifle. I have a Hawke Sport HD 3-9x40 on my HW97K springer, and I manually re-parallaxed that from 100 yards to 20 yards for use at the indoor range by unscrewing the locking ring and shifting the objective lens - if I hadn't, I'd have had no hope of hitting anything I was aiming at.

If you're going to be using the rifle at *really* short ranges, you could even consider a parallax-free red-dot sight - but I wouldn't use one of those on an air rifle beyond 10m, and even then I'd feel iffy about taking live quarry.