That's also incorrect. Oil is effectively unlimited, in the sense that we will stop using it on a large scale within the next 2-3 decades and after that demand will be lower than supply, the same situation we have with coal now.
And farmland is not plentiful at all, even though most of the world is covered in farmland it is always in short supply. That's why Brazil farmers cut down and burn rainforest for farmland to feed cattle, or cut down orangutan habitat to grow palm oil. There is a 1:1 relationship between farmland and habitat for animals.
There's no good reason to need a high powered semiautomatic rifle, anything you need can be done with a bolt action rifle.