I do quite a bit of 22LR target shooting plus 22LR hunting, although not as much as some of the people in this thread (like, Viper's 600 kills per month [!!!]). I have a number of scopes on my various 22LR guns, going from 3-9 to 6-24, 1 inch vs 30mm, FFP v SFP, Mildot v duplex v xmas tree. I only shoot free hand, either standing or kneeling or sitting. Here is my 2 cents.
1. 3-9 is sufficient for small game hunting within 100 yard/90m. But it does not mean it is ideal. I would still prefer have more than 9 power when shooting possum/rabbit sized target freehand. the smaller the magnification the harder it is to keep the crosshair right at the centre of the target. if you always shoot stablised (bipod, shooting stick, etc) you could get away with low power.
2. Having said the above, 3-9 has distinct advantage of not needing to do AO adjustments, cheap, and light weight. my two 3-9 weigh about half as much as my other scopes. There are high quality light wight 4-12 scopes with AO that can go down to 25m, but they are not easy to find. Bushnell had the Japanese made Elite 3200 4-12 AO about 14 years ago, but had discontinued making them since around 2012. This scope was quite light and very good in all aspects, certainly more than competent as a 22LR scope.
3. quite often you do come up with an animal that is super close, like within 10 metres. 3 power at the bottom end is not mandatory but definitely helpful.
4. the only time you need large objective (say, more than 44mm) is when you shoot at low light without a torch. You may want to ask yourself if you do that at all. if you do not, then sticking with 40mm objective is good enough. You can buy really powerful torches for under 100 dollars. I think it is better to spend that money and weight on a torch than a 50mm objective scope.
5. using subsonic ammo (1050fps), a 50m zero gun will have over 10cm drop at 75m and 22cm drop at 100m. Therefore a simple duplex reticle is not ideal. A mil dot scope is better because at 9 power, each dot is 11cm apart.
6. Because of point 5, even 80m and 100m has significant drop difference, you will need to buy a rangefinder to accurately shoot rabbit sized animal.
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