Originally Posted by darthjkf
What is a good deer hunting caliber for the ar-15 that isn't hard to find or expensive in parts?
There are plenty of AR calibers to choose from. But since you're specifying AR15 (as opposed to all ARs (AR10), 243win, 308win, 338fed, etc), I would lean toward 300blk. 6.8spc is also a very competent caliber, but the products that support it may only become harder to find in coming months and years as 300blk gobbles up its potential market.
6.8spc is ballistically similar to a 7.62x39 with generally higher grade bullets and finer accuracy. I've been told by many that 300blk is making it a 'dead' caliber. There's some truth to that, but it'll be around for several more years and can be a fine option. 300blk may be your best option, or you can step up to the AR10 platform that includes 243, 308, etc.