4x4:
A couple of you have mentioned the .243 wssm and also the 25 wssm, I'm not that educated on AR15 platforms guns (that's why I'm here) are these a GOODoption for AR15 platform, feed/malfunction issues?
I did a lot of research when I was looking for an antelope stopper this past summer (Caveat: This is my research and is only as good as my Google-Fu abilities, so...). I was trying to decide whether to buy a 6.5G, 6.8SPC, or other AR upper to take with me this year or to buy a 260REM or 25-06 bolt action. In the end, I bought a 260 REM bolt action b/c it will also throw heavier 140gr bullets, so I can use it as my brother-in-law rifle for elk/deer if he visits. He's not so much of an AR guy. I can also use it with small grain bullets as a starter rifle for my kids, if they become so inclined.
Here was my reasoning concerning ARs.
I'm not a good enough shot to shoot past 400 yards no matter what scope I have.
6.5 and 6.8 are about equal to the task up to 400 yards. 6.8 has more wind drift. 6.5 carries more energy. Either will have enough energy to kill an antelope (or deer) at that distance.
25wssm has more energy than either and beats their ballistics at 400 yards.
25wssm uppers are more expensive. They usually have longer barrels (at least 18") and are a bit heavier uppers than 6.8 (lightest) or 6.5G (heavier than 6.8, usually). This can be alleviated to some degree by fluting the barrel. I didn't expect to be humping this AR uphill and down as I would when hunting elk/deer, so weight wasn't the most important concern. I am aware of only 2 companies make 25wssm uppers: Oly and ... another company out of Minnesota whose name escapes me. Both seem to get good reviews.
Most of the complaints about wssm cartridges is that they are hard to find. I don't think Winchester will stop making WSSM in the near future, but neither do I expect Fed or Hornady to pick up that baton in the near future. 6.5 and 6.8 are about $1/bang for hunting ammo. 25wssm is more but not completely ridiculous. By all accounts, maximum performance for 25 wssm is reached by handloading, but that is true of all cartridges, so that is a wash. I don't intend to handload. If feeding is an issue, that would drive me batty. I have low expectations, but a semi-auto rifle should work between shots 1 and 2 w/out any thinking or praying on my part.
I was looking for a hunting-specific upper. I wasn't going to use it for target contests or home defense. I expected to put 20-30 rounds out of it per year.
ymmv. Good luck hunting!