What upper do you have now? It will probably do the trick. All about shot placement and what type of bullet used.

I'm not a big fan of the .223/5.56 for hogs either. It works, but I just like having more bite. My favorite is a .308, but that isn't an option in your case. I'd go with the 6.8 SPC.

Go with a .30RAR upper. 150 feet per second slower that a .308 with a 150 grain bullet. Ballistics very similar, very accurate and recoil is so much less than a .308. That in an AR15 platform makes it lighter in weight than the .308 in the AR10 platform.

Just get a 6.8 and be done with it.

I have a DMR setup in .223 Wylde. I built it as a hunting rifle and quickly became disappointed and quit trusting it for that purpose. It's great for coyotes, pigs and other critters that I may encounter driving around, but if I'm specifically going HUNTING I have a lot more faith in the .25-06 bolt gun.

While I love the AR15 platform, I've had to accept that as a hunting rifle it's practical range is essentially limited to 200 yards in almost any chambering. It just doesn't do what bolt rifles do as well as bolt rifles, so if you try to make it act and dress like a bolt rifle I think you're handicapping it. You're 5.56/.223 upper really wants to wear a 1x4 scope, not a 3x9.

If you want something that is enough medicine for pigs, 6.8 SPCII is a GREAT option but it can be expensive to feed. .300 BO is easy to suppress, all parts except for the barrel are completely interchangeable, plenty of punch for pigs at close range but, again, it can be expensive to feed and difficult to find good hunting ammo.

Finally getting to the point, I think that if you have a .223 upper set up for day gunning, a 7.62x39 upper set up for night (or day/night) gunning and your grandfather's .30-06 you have everything covered. Political hiccups aside, there will always be a plethora of x39 ammunition available relatively inexpensively. Hornady offers an outstanding selection in its steel cased SST and you can buy plinking ammo for about $0.25 per round.

.300 AAC BO = ~$1.10/round

6.8 = ~$1.00/round

In other words, part of what ARs do far better than your grandad's .30-06 is "fun shooting". It's not necessarily THAT fun if a 30 round magazine is $30.