”Scarieness” is an easy sell for anyone inclined to emotional decision-making (most gun-control types), but I think the popularity, and sheer numbers of AR-type weapons in circulation is what really gets under the lefties’ skin.
RE: the new .277 Sig Fury cartridge, what’s been lost to history is that Army Ordnance did testing in the 1920s and determined that the Goldilocks cartridge — the perfect balance of lethality, recoil and ammunition weight — would be something in the .27 to .28-caliber range. That’s why John Garand built the M1924 prototype for his M1 in .276 Pedersen. But then the Secretary of the Army, a certain Douglas MacArthur, insisted that the new battle rifle be chambered in .30-06 Springfield on account of the Army had 3 billion rounds of the stuff left over from WWI.
Garand’s prototype also used a detachable box magazine, but Army Ordnance feared that would lead to ammunition waste so they specified that all submissions to the test would have to feed from a fixed internal magazine of no more than 10 rounds capacity.
There’s a lot of pearl-clutchers who bemoan the new .277 cartridge because it’s not a .30-cal when in fact the .30-cal was never the top choice. The .30-cals (.30-06 & 7.62xs51) only won out because it was more economical to shoot up all the old stuff.
And Garand still gets criticized for not having the foresight to give his masterpiece a detachable box magazine in the first place when in truth he already had seen the writing on the wall in WWI the form of John Moses Browning’s detachable box magazine-fed, select-fire M1918 BAR. It’s Army Ordnance, not John Garand, who were responsible for that omission.