With correct shot placement, just behind the eye, even a 177 will do the job. A good break barrel or under lever in 177 or 22 makes you independent of any air source. The distance at which you can reliably hit a 2 cm circle would be your sensible range. Choose a good pellet like JSB Exacts or H&N FTT and zero your gun regularly. 4-5J on target is enough. A quality PCP will extend your range, because they usually have more power and require a little less skill to shoot accurately.
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