50 yard springer

I second what Mark says above, of the few (ish :)) springers I have, my Diana52 makes me feel like an expert target shooter !

There's no doubt that Springers are less forgiving than PCPs. Springers DO require an almost Zen like melding of gun to man - which only comes thro' many hours of practice. In my experience only a very few can achieve both accuracy and speed with a springer (the person I'm thinking of used a BSA Supersport and iron sights so fast you didn't notice him reloading - shot about 15 Rats in quick succession in a barn). The point being he'd always used that gun and I don't think he needed to look thro' the sights at all, just matter of shoulder, then trigger,

If you feel you need more than 12 FPE in .22" then I believe 19-25 (FPE) to be near perfect with a spring gun.
 
Of all the spring guns I've had, the low/mid powered ones have always been the "best". If you really need more than 10-14 fpe, I'd start looking at pcp's.

Power is grossly overrated, always has been. Its a difficult thing to get used to and get over, took me around a decade and quite a few poor purchase choices before it finally sunk in fully. Placing a pellet correctly is "almost" all that matters, however "power" isn't all just to impact and penetrate a critter. It makes for flatter trajectory, better wind bucking, etc, all which help alot in placing that pellet!

Like others have said, springers seem to shine at 30-35 yards and under, which I would agree with. I prefer .177's in the guns I have, at closer ranges it takes alot of difficulty of trajectory out of the equation- the available power is a mute point for me. 

What finally (Finally!!) ended all doubts of needed power levels for me was a few squirrel hunts with a scoped FWB300s match rifle. The gun sounded lethargic, almost like you could put your hand over the muzzle and shoot without harm. I believe it was around 6fpe at the muzzle. However, what it did offer was insane accuracy AND shoot-ability. I remember aiming on the first big fat fox squirrel with it, perfect placement and total confidence in where I was going to hit, and was rewarded with several drop dead shots.

When shots exceed 30 yards, you can benefit from the help of recoiless pcp's. While I could shoot with surprising accuracy out to 50-55 yards with that lethargic FWB 300s, wind (tiny breezes) made accuracy exceedingly difficult, and the extra power of larger calibers+pcp's would really start to shine.

 
Either a Hw97k in .20 cal. or a R1 in .22 cal. will fill your needs.
I have hunted Californian ground squirrels with both and have been very successful. My 97k was tuned by Paul Watts and will send a 11.42 gr. Beeman FTS at 780 fps for just over 15 ftlbs. My .22 cal. R1/V-Mach equipped with a 13" barrel and V-Mach RaceBrake send a Defiant 16 gr. pellet at just over 800 fps for super smooth 23 ftlbs ground squirrel killing, wind resistant, projectile. Early spring before the grass gets eaten down is when the R1 is the tool to use as it can blast through thin weeds and grass to allow the lead sleeping pill to find its mark. Likewise those squirrels that like watching from the top of fence post need to know at ranges over at 100 yards that they are not safe from the R1. The 97k is just so accurate that when the conditions are right, grass eaten down and no wind, that making multiple shots in a row on squirrels out to extended ranges makes the 97k almost shoot with PCP accuracy. My best 5 shot practice group with the 97k at 57 yards is a hair over 3/8 inch of a bench. That's accurate!
Sadly, these guns don't get the use they once did as I have been seduced by the "DarkSide" and shoot an AZ tuned .22 cal.Hw100/STB. Scary accurate even with non-lead pellets.

Good luck,
Mike