I have a Theoben Evolution .20 caliber gas ram, with the walnut thumbhole stock. I like the gun - a lot.
It is easily one of the most beautiful of all the guns I have, including my R-9, a TX200 Mk2, and an Air Arms 410ERB. The finish, stock, and feel are like fine furniture. I've said it before, it is the one gun that gets gasps from people when I remove it from the case.
I only discovered after owning the gun for two months that the walnut thumbhole stock has an adjustable buttpad. Very nice, saves buying an aftermarket pad. They are a huge assist to getting the gun to fit to the shoulder right and finding your weld point.
I love to shoot the gun, and I am becoming more and more impressed with the .20 caliber pellet. Yes, the selection isn't as big in .20, but come on, how many different pellets do you really shoot anyway. It like medium weight pellets best, the heavy ones (13 gn and up) are less suited to the gun. Beeman FTS, H&N field Targets are my favorites; Crosman Premiers and JSB's are a little heavy but can work.
The .20 caliber pellet is great - it hits hard with lots of speed, fairly flat trajectory. This is a 12 fp gun that hits a lot harder than you expect. I'm ready to start looking for my second .20 cal gun. Sometimes I wish my R9 was a .20, too.
I'm tired of the Evolution trigger comments. These comments are mostly made by people who have not shot the gun, and are parroting internet comments they read elsewhere. It is a trigger designed for hunting, and bragged about by Theoben, while getting panned on US websites. All I know is that, after adjusted to your liking (with a trigger gauge necessary), it is very predictable and I rather like it. Mine won't adjust below 1.5 pounds, but I haven't had it tuned. For hunting, that's fine. Besides, everyone tunes Rekords, too, so if it isn't that great out of the box, and needs tuning, how great can it really be? Answer - not better, just different and suiting certain tastes.
What I do know is that it consistently works. I regularly get one hole groups at 10 yards, ragged holes at 20 yards, and cloverleaves at 30 yards. Better than my R9 .177, about the same as my TX200 .177, and not quite as good as my 410ERB .22. So accuracy is superb. It is obviously not bad enough of a trigger to affect my aim. Your mileage may vary.
The gas spring is nice, too. Less twang, more thunk and forward recoil, a little harder to cock (due to a short barrel on the Evolution, almost a carbine). It's nice to leave it cocked when hunting - no worry about spring wear(although, I'm not convinced leaving a spring cocked for an hour or two causes any excessive wear) and no noise cocking it while a target is nearby. The gun is very adequate out to 30 yards, and I can easily hit a 2" target at 40 yards - past that and you are losing ft-pounds.
It has little hold sensitivity, much less than most springers - gas springs don't torque and twist with lots of lateral and rotary movement when you fire as a strong spring gun can do. The movement inside the gun seems to happen quicker - it's all over in a quick thunk.
Not everybody likes gas springs, but I am very happy with its performance and feel. I would choose it over a conventional spring if a gun was offered with both options.
