Is the AR-15 an effective weapon for civilians to use against domestic terrorism?

[MuscleScience]

Can you tell me why it is we never adopted a .284 seeing as how it has the greatest ballistic coefficiency capabilities of any caliber ** that can reasonably be put into a standard issue weapon with any sort of cost effectivity**

I am bewildered as to why it has been so ignored in everything but long range shooting.
In long rage shooting it is king.
One would think it would be the US militarys primary round across the board.

Btw I dont mean the .284 win round I mean that caliber in general.

Just a small example:

7mm Remington Magnum outperforms the 300 Remington Ultra Mag at 1000 yards. The difference is a BC of 0.640 for the 7mm versus 0.410 of the 300.
These are generalized of course but step that up to a 7mm RUM vs a 338 or 300 RUM and it still beats it in most loads.

Fact is for small arms a .284 caliber bullet can be utilized to a higher BC than any round I have seen with less propellant. It is more cost effective to 1000yrds than any I have seen. Bearing in mind I established all this to my self when I was a teen. Dont know all the new calibers after 2005 or so.

Seems to me small arms today should be effective to 1000 yrds within reason without tumbling bullets or totally pissing in the wind.

Jmo... Though I never organized the most powerful military in history and know dick compared to armorers today.

This is my dream build, I will use it as a Hog Gun. I’d have it built but I just can’t decide on the Caliber. I guess I could build a couple of uppers and just swap out. But I’m kinda cheap lol