Why was your first assumption with a failure to fire that the mag might be bad?
Also, why not try refiring the problem rounds in the same gun, rather than another gun?
Everything I saw in your video looked like poor ammo. From failure to fire, to random ejection pattern, to random feeding/ejecting issues sounds entirely to me like crap ammo.
But I will go ahead and agree with you on the folding stock issues...
Also, don't expect much in the way of customer service from the XCR. The owner of Robinson Arms is an arsehole and notorious for his thought that you should feel honored to get any service from him on his weapons.