Again, you gloss over important but inconvenient "facts", which is what makes it absolutely a narrative.
You're entitled to your opinion, like always, but did you really make a single argument that isn't subjective on a practical level?
o Penetration/energy/momentum? Increase caliber, bullet mass and sectional density (far beyond what's possible with BO)
o Cost of ammo/bullets/reloads? Shoot .223, it's even cheaper (do you really need max penetration with every round of thousands, to the point that cost even matters?
)
o Standard mags/lower? Shoot .223, see above.
o Still insist on shooting heavy-for-caliber loads? Get a new barrel, there's nothing to it.
o Off-the-shelf subsonic ammo / its availability in the US? .45ACP for 230-300(+)gr factory ammo, rimfire for cost-efficiency.
o AR with measurably better hypersonic ballistic performance? CMMG Mutant, LAR-47, MARCK-15 etc. (AK mags are common and cheap too) or a AR10-platform rifle.
So... what's left at this point? The situation where one absolutely insists on having a standard AR15 lower with standard mags, with a barrel installed on a stock gun by the manufacturer, in a caliber no larger or smaller than .30, regardless of the cost of factory ammo but reloading for maximum ener^H^H^H^H terminal ballistic penetration for the said caliber at every round with heavy-for-caliber bullets, seemingly including plinking ammo.
If you want to rig it this way, then the BO is the be-all, end-all round of the entire universe.
Highly off topic but there's distinct relevance in the situation: This reminds me of a similar spontaneously facepalmy feeling elicited, back in 2006 I was driving one of our show cars, Veilside "11th Commandment" (a Mk.4 Supra of Tokyo Motor Show fame) just north of Düsseldorf on Autobahn. At 140-ish MPH cruise speed a bright yellow Lamborghini Diablo flashed to pass and I gave way. And chase. The Lambo floored it, so did I, and flew by him all the way to 200+MPH, with more than twice the power he had on his disposal. He followed me to a truck stop fifty miles later and exhibited a galore of excuses. But yours is modified! (Heck, yes) But yours is Toyota! (Yep, or actually built on Toyota bodyshell by Veilside) But my Lambo has wider tires! (So it seems) But mine is more expensive! (Actually, ordering one of these from Veilside set you back $150k or so, not including the price of the Supra) But mine is LAMBORGHINI!!! (File a complaint, then, if they sold it to you as the the ultimate king of Autobahn)
Nice Lambo, though. Looked good. Teenagers hang posters of it on their bedroom walls. Not my cup of tea, though, because I prefer real-world performance over hopes, dreams and perceived imagery.
Deja vu...