I would like to hear feedback from owners of any of these type AR's. Am considering a build or buying 1. thanks

You might check the predatormasters forums if you have not already.  

I have a stock Olympic 25 WSSM, just went to Cherry Ridge yesterday, put 10 rounds inside 3" at 300 yards w/ handloads.  I suspect the 243 would perform about the same.  Just needs a better trigger.  Fine shooter as is, but if you want to hunt suggest you assemble one with a Dedicated Technology (Mike MIlli) fluted upper to save weight.

Im bumping this question after a search found this thread.

Im wanting to build an upper with the 243 WSSM for long range sod poodle slaying.
Accuracy Systems makes a few uppers and  I found the price interesting but no real feedback to reliability.
I know of only them as far as complete uppers.

My buddy said he read on one of the varmint forums that case extraction was an issue with a couple of members.Other than that no info.

My questions are mainly if a bolt is made that will work in the AR uppers with the WSSM rim diam.........I assume you cannot open the 223 bolt face up that far. Barrels wouldnt be that big an issue but then again.........Im not sure.

Ive also been toying with the idea of a wildcat 6.5/243WSSM

Would I be better off just purchasing an upper.....pre-made? Ive considerable skills in a machine shop,just not alot of time.

Quoted: Ive also been toying with the idea of a wildcat 6.5/243WSSM

I've also put a lot of thought into this one. I'll get back with you sometime & share thoughts if you like. I have a 3.30 Am wake up call & have too get a little shut-eye right now. The biggest hurdle IMO is mag length, I think the best workaround is going to be an even shorter case. M9

I have an Oly 243 WSSM with a 6 x 18 Sheperd. So far an absolutely awesome long range weapon. Still playing with loads but at 400m my groups are well under MOA. Very tight rifle and the SUM barrel is top notch.

I have an Oly 243 WSSM upper.  To my surprise it arrived with a SUM barrel.  It EASILY shoots under .5" groups at 100 yards and I don't consider myself that great of a marksman (I was actually surprised I was able to keep it under .5" groups reliably without messing it up with poor technique, but I did).  

My 2 points for consideration.  
1.  VERY tight fit to my RRA lower
2.  The semi auto limits reloading options.  I haven't been able to get quite the velocity I had hoped for out of my 70 grain varmint bullets, yet.

I have one of each of the WSSM chamberings.  The accuracy of each of them has been very good.  I have spent more time in load development with the .243 WSSM than the .223 and .25 WSSM combined, but the .25 is quite easy to load for and I've takein some fine big-game with it, as well as some long-range varmints.

The .243 WSSM is a little on the fickle side for load development.  I have been able to acheive excellent accuracy, velocity and SD with bullet weights from 70 grain up to 90 grain.  My use for the .243 never involved the need for a bullet heavier than the 90 grain bullet, so I just haven't done anything with the heavier bullets.  What I basically settled on was an 87 grain Hornaday for long-range varmint/predator and an 85 grain Nosler partition for white tail.  

I have only heard of a couple of extraction issues.  One involved a chamber with a nasty scar and the other involved a .25 WSSM with a short barrel, slow-burning powder and a heavy bullet.  It actually extracted OK, just bent the rims in doing so.  Feed and function has been great.  I have heard of many people running into trouble resizing the brass and not getting the shoulder set-back far enough.  If you put a re-loaded shell in your chamber that is 1/2 thousanth longer than the chamber, and slam the bolt shut, it will stick HARD!

All in all, the .243 and the .25 have been very popular, reliable and accurate.