Just to update the backlog timeframe currently going on at Carrier Comp:
M4 7 round titanium mag tube order placed on March 5th. Just received a call (850 area code) to arrange credit card payment and to inform me that shipment is expected in approximately 2 weeks. So, slightly longer than the early to mid-June estimate from a month and a half ago.
They are very pleasant to converse with, both via email and over the phone.