Pistol crossbows are a joke wozza - fun for the garden but nothing to hunt with.
You have a duty to your prey to be able to kill it cleanly and without suffering. If you don't have the right tools, training and experience, then you shouldn't even attempt the shot. If you cant hit a 2p piece 10 shots out of 10 at the intended range, and are using the right weapon, range and ammuntion type, and have a safe backstop, and are aiming in the right place for a clean kill, then there should be no question about risking the suffering of an animal.
Sorry to lecture but being skink (skint?) is no reason to risk cruelty. If hunting interests you, I would suggest the first thing to do is to join a hunter field target club - its a great way to learn to shoot safely, estimate ranges, learn trajectories and try out a variety of types of air rifle. When you have the shooting ability down pat, get an experienced hunter to teach you the field craft to get close to your prey (and it will be close with airgun hunting rabbits). That way you will learn all the right skills without risk. Hunting and eating what you hunt is a fine activity, but clearly the risks and hence investment of time, effort and money to minimise those risks is much higher than many other Bushcraft activites.
[boring old shooter mode off]
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