I've been looking into some of the unusual offerings that are available, or soon to be available for the AR. Alexander Arms has the excellent 6.5mm Grendel, Oly is offering .223WSSM, .243WSSM and will soon have a .300WSSM. Remington 6.8mm ammo will be hitting the shelves in the not too distant future, and I feel it will be an excellent upgrade for a wildcat AR. Then there are the .458-.500 bowling ball launchers. Of course, I'm not overlooking the AR-10 in 6.5mm or .308 either.

Who has experience with wildcat cartridges? How are they in terms of accuracy and reliability? Is it still fun to shoot an AR at a buck a bullet?

Yes, it is still quite fun to shoot at $1/shot.  However, once I got the registered reciever nothing else gets shot very much.

I decided to go with a .308 bolt gun for hunting, or my AR10.

I would happily jump back on the 458 SOCOM bandwagon, it just didn't fit with my shooting style at the moment.

As too accuracy, the 440 Corbon Mag upper I had with a 1-4 power scope could touch all 5 shots at 50yds.  It would open up a bit at 100yds, but the shots were still all touching.  The 50AE upper was similar though the groups always seemed to have one flier.

The 458 SOCOM was never shot for groups, but out to 100yds it was one of those point and shoot type weapons.  Plnety accurate enough for snap hunting shots to 100yds.

Ask GOTM4 to post pics of the results of his last season with his 50 Beo.  The huge hole speaks for itself.

In terms of accuracy and reliability, they are (or can be) the same as the "normal" 223 AR.  As to hunting calibers, it depends a bit on where you live as certain states have minimum caliber requirements.

You can get the following (just a small part of the 50 + or so calibers the AR can be chambered in)
6 x 45
6.5 Grendel
7.62 x 39
300 Whisper
6.8 SPC
7 BR
30 HRT
338 Spectre
.499 LW
.50 Beowulf
.458 SOCOM

and the Oly Arms custom uppers in .223, .243 and soon .308 WSSM

Shooting at $1 a shot is not much different than blasting .223 to me, in both cases I have to find time to sit down and clean my weapons ... and time is what I have little of ...