I've owned a CZ V22 dedicated upper but there were 2 problems: the bull barrel was too heavy for most kids to lift for very long and I could NEVER get the thing to run reliably. The out of battery discharge that blew the feed lips off of one of the magazines was the last straw. I'd love to get a dedicated upper but the $500+ makes it not a priority right now...maybe sometime. I did decide to get a Ciener conversion, even with the reputation of crappy service and iffy quality. From the reports I've seen, many people have perfect reliability in their unit but somewhere around 10-20% (my guess) have significant problems. I'm telling you what I had to do to get mine running...if you have similar symptoms, maybe this will help you. I got one of the few that Midway has in stock from time to time and at the dealer price. I installed it in a J&T M4-gery upper with a 16" 1:9 barrel on a DPMS lower with a RRA NM 2-stage trigger. Loaded up the recommended Remington 40 gr HVs, chambered a round and...nothing. The same thing happened with Remington 40 gr, Federal 36 gr bulk pack, Remington 36 gr bulk pack, and Aquila 40 gr. All of the problems below happened with all of the type of ammo I had. At this point, I was ready to throw the thing away, but a sense of pride, stubborness and a real desire to not let it beat me prevailed. So...on with the saga. Problem #1 - 75% failure to fire There were only light firing pin strikes on the rims. I swapped out the RRA hammer spring with the original hammer spring and finally got reliable firing. The trigger is heavier (moved from about 3-4 lbs to 5-6 lbs) but is still very crisp . Problem #1 solved. Problem #2 - 90% failure to extract Once I got the thing to fire, 9 out of 10 times the empty case wouldn't extract. On the Ciener kit in area #1 shown in the attached picture, there is a ramped cut in the metal surrounding the chamber that the extractor rides up into. When I would hand cycle shells with the unit out of the rifle, I noticed the ramp kept the extractor away from the rim until the extractor had ridden over the rim. In addition the extractor hook face wasn't square. I used needle files to both square up the extractor face and deepen the ramped cut. Take only a little metal off as you do not want get into the chamber area. Hand cycling and live fire now shows that the extractor is pulling the case out. Problem #2 solved...except now I found the next problem... Problem #3 - 50% failure to chamber and failure to fully extract Now that the unit was reliably firing and at least starting to get the shell out of the chamber, I found it wouldn't fully chamber or completely extract. There was no problem with the cartridge feeding out of the magazine but it would stop chambering about 1/2 way in. After manually pushing the bolt forward and firing the cartridge, it would start to extract then and then and the extractor would slip off the very small rim of the case. The first thing I did was take a .22 bronze brush, oil it and really scrub the chamber area (area #2 in the picture). I also lubed the guide rails and polished the bottom of the bolt in area #3. With that treatment, an unfired round would easily drop in the chamber and come out with a fingernail under the rim. With that, the unit feeds, fires and extracts about 99.5% of the time. But that led to... Problem #4 - 20% failure to eject In about 1 out of every 5 shots, the empty case would not eject and got hung up in the works. Often I had to take the upper and the unit out to get it cleared. I notice that the top of the magazine feed lips showed that they had been rubbing on the bolt (area #4 in the picture). Also the left feed lip is right next to ejector. I stoned the top of the feed lips and tried it...same results. I suspected the feed lip was interfering with ejection but didn't want to bend it because the mag fed reliably. I ordered 2 Black Dog Machine mags from Brownells and tried them (picture of the magazine shown below). 100% reliable!!! Everything works exactly like it should. Plus, these mags are 1) cheaper than Ciener's, 2) hold more, 3) have a bolt hold open feature, 4) look like a regular AR mag, and 5) are smoke colored so you can see how many rounds you have left. I threw the original magazine, #5 in the picture, in the reject bin...only to be used if i get amnesia. Problem #4 solved. So in the end, I probably shouldn't have put this much time into it, but I now have a 100% reliable unit with no additional expense...just some frustration and problem solving. It is reasonably accurate (3-4" at 50 yards with a red dot...probably better if I would mount a magnified optic). It runs the best with the bulk pack stuff, so that is a benefit. I think Ciener either needs to tighten up the design or tighten up the manufacturing/quality control...obviously some dud units are getting out. My advice to you? Buy a dedicated upper, wait for some of the other units coming out (like CMMG). If those are not possible, buy a Ciener...and cross your fingers.