Good surplus 7.62 NATO ammo is $100 per 200 rounds. If you buy a lightweight .308 Winchester mountain rifle, the recoil will be high enough to mimic a larger cartridge in a heavier rifle. You can practice relatively cheap, perhaps less than the cost of reloads. If you go prairie dog, woodchuck, pond turtle, poisonous snake or other type of high volume varmint hunting, you will be doing somebody a favor and in a real fire situation you do not notice recoil like at a rifle range, and it is real world practice with varying wind direction, etc. Varmint hunters are the deadliest big game hunters, for good reason due to their high volume of fire practice.