Hey just wanted to let the spikes gen 2 billet upper owners know,  if you purchased your upper 6 months or longer ago, chances are it's a little loose on most of the lowers, well after getting a hold of spikes tech guy about my gen 2 upper and lower not having as tight of a fit as advertised I was glad to be informed that they caught the issue and have been making them with maximum material on the front and rear lugs tightening up the fit, still waiting for the new version to get here but thought some of you might find this info useful.