Hi and first of all welcome to the forum ☺️ To best answer your question, we would first ask you a few. Now you may not nessesarily know the answer to some of them, but that's ok. Now some of the questions may be likely to be met with some resistance, as a lot of people disregard Co2 as a means of propellent due to its variation with temperature. However, we have always said that, sometimes budget is a massive deciding factor in what you want from an air gun. Co2 can be cheaper than its spring or air powered cousins and sometimes it is better for what you want. 1) Target, Pest, or Fun? 2) Replica or Performance? 3) Budget? For target guns you are looking at the pellet firing rifled air pistols such as the Webley VMX and the Umarex Beretta M92FS, however these do tend to remove the realistic side of the gun. For pest control pistols, you don't have a great many of them due to the calibre restrictions however a good rule of thumb is if it is a single shot bolt action pistol, these tend to deliver closer to the UK power restriction of 6ft/lb (~8J). If you are struggling with choosing one, sometimes the best way is visit a local gun shop and hold the gun, as this can be a massive deciding factor in your purchase. Please remember that your budget is always important to keep realistic, pistols can range from £90 all the way up to £500, and sometimes the budget does dictate the quality. Don't expect a £90 air pistol to perform well or for any length of time. However on the other side, a £500 one may not quantify its price to performance, it is normally down to build quality of the gun. Besides probably confusing your choices more, we hope this kind of helps with your choice 👍