a sidearm isn't that much different, it really depends on the numbers. there's significant numbers of sidearms that required changes you seemed to think make a new fielding logistically impossible. nobody claimed the new fielding would happen overnight either. and sure i guess you're right it's not replacing literally every m4, but they are replacing the m4 as the service rifle for frontline troops, which means over 100k rifles. the m7 will be fielded in higher numbers similar to service rifles of european armies, and orders have been placed already. the logistical nightmare you described is already happening
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