I forgot to mention there are people who bought Spec 180 MCR lowers who are still looking for an extra alternative calibre upper for use with it, so even if its too late to sell them a separate lower, TNA could happily sell them a complete TNA Enhanced MCR compatible upper or the parts to build one. It would probably make sense to sell the complete uppers with rifle length pistons and adjustable gas blocks, so even if the use TNA WK compatible bolts they will have additional differentiation from the standard WK, aside form the nickel plated, improved charging handle carrier and other improved TNA upper enhancements.