The Roles and Weapons with the Squad

[Compost]

We can agree on that.

We can also disagree on all the rest. While your arguments make take technical sense, they are less practical militarily or tactically. I, for one never agreed to any 9mm cartridge; I've always argued for 10mm or larger for pistols and SMG. Your 6.6mm caliber is IMO too light for the Company level machinegun and so should be avoided; all small arms in a Battalion should be of one of two calibers, pistol / SMG and rifle / MG. A medium MG is also required at about 12-15mm. My observation has been that the 20mm is not an effective military cartridge (it is both range and payload limited) and the 20x102 is particularly poor. IMO 25mm is a far better top end choice. A 30mm would be better yet but the size penalty is too great unless it is restricted to Armored / Mechanized forces (which probably should occur).

However, neither your nor my solution is likely. Nor is US use of a bullpup configuration likely (quite sensibly in my view...)...

However 6.6mm is spot-on for what is needed at squad/platoon level, with 7.62mm magnum at platoon/company. The bookend at 20mm is a realistic limit for a man-packable rifle type weapon to equip some pioneers and snipers for EOD and anti-material tasks.

You surely included 25mm and 30mm as vehicle rather than man-pack weapons. US infantry already have plenty of variety and weight with 9mm Parabellum, 5.56mm NATO, 7.62mm NATO, 7.62mm magnum and 12.7mm Browning. And that's before 8.59mm magnum is added as a gap-filler or replacement.

My last words (on this thread) regarding bullpups are a repeat from way back.

A future that insists on the bullpup configuration would be as backward as a present that insists upon the fwd-mag.