I have Sportsters in .22LR, .22 Mag, .17 HMR, and .17 Mach2. I use my .22 Mag for coyote hunting by limiting shots to 100 yards. I believe my .17 Mach2 is a hair more accurate than my .17 HMR (smaller groups by a TINY bit) but the .17 HMR is a bit more powerful, For your 70 yard distance I believe the .17 HMR would be enough gun and extremely accurate for smaller varmits, fox and down. If I knew the prey would be primarily coyote to fox size I would go with the .22 Mag. If the prey was smaller, fox and down, I would go with the .17 HMR. You will do fine with either one. For squirrels, crows, rats, etc., the .17 Mach2 would be just the ticket. For cheap shooting a .22 LR would lead the pack but would not be as accurate or powerful as the other cartridges mentioned. Accuracy, energy, noise, expense are the 4 variables I would think you have to evaluate. For the amount you will be shooting I think you can disregard expense (ammo cost) so I would remove the .22LR from the equation, especially at the distance of 70 yards. Good luck....<><.... :grin: