I took both of my AR-15's to the range, one is all RRA parts on a stag lower, the other is a CAV lower with model1sales parts.

I shot wolf out of USGI mags, and out of the cav rifle, it shortstroked about 80% of the time, at first it would eject the case but fail to pick up a new one, as we continued firing, it would draw the case out of the chamber, but then slam it into the lugs, requiring me to complete the ejection manually. I swapped the mag out and used it in my RRA rifle and it worked fine, except for 1 light strike/hard primer issue. I have had NO problems with these guns before; the RRA rifle has had over 800 rounds through it, the cav rifle has only 100 or so, being brand new. It was properly cleaned and stored, and both have functioned with wolf in the past.

To me this clearly indicates a mechanical shortcoming of the cav rifle, so where should I be looking first?

Does the bolt lock open after you fire the last round in the magazine?

It does sound like a shortstroking problem.  Check the screws on the carrier key to be sure they are tight and properly staked.  I would also take a close look at the gas rings, to see if they possibly have been damaged in some way.  In fact, if you have a spare set of gas rings I might just go ahead and throw them on, just to be sure (I've had some that were bad with no visible signs of damage).     If neither of these things help, then try using the bolt carrier from your good rifle (use the same bolt).  

Good luck.

Wolff ammo = lots of CLP for lube (upper bearing surfaces) and real good cleaning after each session of shooting.

Bore solvent like Hoppes or Sweets copper solvent will need to used to clean the copper out of the barrel, but the bore solvent needs to be flushed out before final lubing the rifle with CLP. Also in regards to the other parts, use CLP as both the cleaner, then as the lube.

Also, when running wolf ammo, you need to lube the upper bearing surface a little more than normal with CLP.

To keep it short, had you cleaned the rifles correctly, and given them a fresh coat of CLP before shooting, the rifles should have run.  Next time you run into this problem at the range, pull the B/C, give it and the upper bearing areas a fresh coat of CLP, and see if it solves the problem.  Trust me, more AR cycling problems have been solved with nothing more than a can of CLP then any smithing.

As for how to buy CLP, BreakfreeCLP in the large spray type can be had at Wally world for less than $10. If you don’t find it in the sporting goods section, go look over in automotive section.

http://www.ar15.com/content/guides/maintenance/

Thanks for the advice, I pulled the BC and it looks like the gas key is loose compared to my "good" bolt./bc. I use CLP on my guns, and they were properly cleaned, so I attribute the problem to the loose key. I will take steps to remedy this when I have more time.

Sorry about that, I kind of blew threw your post and responded a little too soon.  
How’s it go again, READ, AND THEN POST!!!!!!

Looks like Triple_D was dead on the mark in regards to the checking the key, but I will add since this is a Model 1 carrier, you need to pull the key and check the mating surfaces between the two before reinstalling the key.  

On some (read a few years ago), I have had to de-bur the allen screw thread top lips on the carrier to get the surface flush, align the key to carrier gas port channels, and then hand lap the two together to get the correct seal.

Also, using new key screws wouldn't be a bad idea as well. If the screws where over torque’d or someone tried to peen the head of the screw instead of flowing the key metal into the screw side spines, the screw could be on the verge of snapping when you go to re-torque it to the 35 in lbs needed. Trust me, a few dollars spend on new key screws is much less evil then the fun you will have digging out one if you snap the head off. I haven’t talked to anyone over at Model 1 in years, but you may luck out and they will send you replacement key screws for free.

Quoted: Thanks for the advice, I pulled the BC and it looks like the gas key is loose compared to my "good" bolt./bc. I use CLP on my guns, and they were properly cleaned, so I attribute the problem to the loose key. I will take steps to remedy this when I have more time.

I had the exact same issue except a stag lower w/ model 1 upper.

I found that the gas key screws were not loktited in place and the stakes were pretty shallow.
corrected both and now is 100% no futher failures in over 1K rounds.

Loctite is used as a cheap gasket compound to sell off the key/carrier mating surfaces instead of lapping (thin coat between the two).  With the heat generated, trying to use the Loctite on the screws to lock them in instead of penning, it is not going to last long, and the screws will work loose.

Nothing wrong with using Loctite to make a gasket, but if you do have the chance/time to lap the key into the carrier, it is just a more solid correction in regards to longevity.