So your point is we should replace our M4's with 357mag AR conversions or 300 blackout? How's the 357 out to 300 yards?
Don't know. I guess it would be like using a mortar.
Where rifles are illegal for deer a PCC is a viable option to a shotgun. That was my point. Penetration is pretty good with 158's at 100 yds. I would venture a guess that most deer in the US are shot within 100 yds. I used to hunt with a rifle in the west and most of the deer I took were less than 100 yds. Out here archery and muzzle loaders have become more popular than rifles, which are legal.
I'm not making a case for using bows, muzzle loaders or a 357 in combat. Deer don't shoot back.
The original design for the M-16/5.56 NATO was a weapon using a 20" barrel. When the military adopted the M4 carbine things went downhill and they've been patching it up ever since.
But I think you know that
Barrel length SS109/M855 V4 bullet velocity V4 velocity loss
210 mm (8.3 in) 723 m/s (2,372 ft/s) 41 m/s (135 ft/s)
240 mm (9.4 in) 764 m/s (2,507 ft/s) 32 m/s (105 ft/s)
270 mm (10.6 in)796 m/s (2,612 ft/s) 29 m/s (95 ft/s)
300 mm (11.8 in)825 m/s (2,707 ft/s) 18 m/s (59 ft/s)
330 mm (13.0 in)843 m/s (2,766 ft/s) 23 m/s (75 ft/s)
360 mm (14.2 in)866 m/s (2,841 ft/s) 12 m/s (39 ft/s)
390 mm (15.4 in)878 m/s (2,881 ft/s) 14 m/s (46 ft/s)
420 mm (16.5 in)892 m/s (2,927 ft/s) 14 m/s (46 ft/s)
450 mm (17.7 in)906 m/s (2,972 ft/s) 9 m/s (30 ft/s)
480 mm (18.9 in)915 m/s (3,002 ft/s) 7 m/s (23 ft/s)
508 mm (20.0 in)922 m/s (3,025 ft/s) -