Mine has all sorts of problems,short strokes,FTE,pretty much useless........

I know two different guys that use them in their M16s with no real problems.

I mean the 22 lr. Makarov conversion  kits that Kvar was selling a while back.Has a aluminum slide and a barrel you drop in.

Does it include its own recoil spring or do you have use the original one?  Original spring can be extremely stiff which would explain these issues.

No,it comes with its own recoil spring with the drop in barrel thats threaded with a metric barrel bushing.I made a adapter to use my 22. suppresser but I want to get it to work well first before I try the can.The whole set up looks like its well made but I have yet to empty a full magazine with out some sort of problem.I get too many stares clearing the jams for FTE at my range.Some one always chimes in it should be lubricated more or too much lube.......lots of experts that have never seen this type of gun or its commie junk thats was no good to start with,let alone with  a 22 lr.  conversion kit.Yikes

Mine works fine but needed a little bit of coaxing to work reliable at first.  The rails were a little tight and it was rubbing on the sear spring where it loops over the slide release.  The slide is soft so it will wear in pretty quickly, I sniped a little of the spring and worked the slide until it had a good rail fit than put it all back together and it has shoot fine ever since.

These are in stock at Apex.  I'd buy it for the novelty value, but $299 is a little steep for me.  If it came  with more than one mag I'd think about it: