Back to the OPs original request:


Yes, there IS a definition for an "assault rifle" and it has nothing to do with cosmetics.

It's quite simple, really.


An assault rifle is a semi-automatic rifle with a detachable magazine that shoots a medium-powered cartridge and has a maximum effective range of about 300 meters.


A "medium-powered cartridge" is a rifle cartridge more powerful than a handgun cartridge and less powerful than a hunting cartridge.

Thus, the M-1 (.30-06 cal.) and the M-14 (7.62X51) are Main Battle Rifles, not Assault Rifles.

The M-1 Carbine (.30 cal.) original M-16 (5.56 NATO), the AK-47 (7.62X39) and the Ruger Mini-14 (5.56 NATO) can all be classified as assault rifles.


What makes things a bit complicated for most people is that the M-16A2 (with >62-grain bullets), its civilian counterpart the AR-15 and some Ruger Mini-14s have been enhanced and are no longer assault rifles, but high-power rifles.

This occurred when enthusiasts developed the platforms for long-distance shooting.

They had to change to a heavier bullet to reach those ranges, a different twist rate in the barrel to stabilize the heavier bullet, heavier barrels to prevent distortion from heat and a host of other small changes.


The first assault rifle cartridge had a 55-grain bullet.

The second cartridge adopted a 62-grain bullet. A tighter twist rate was adopted at this time to accommodate the even-heavier tracer bullets.

The long-range cartridges use a 72-90 grain bullet in a barrel with an even tighter twist rate.


These long-range cartridges are no longer considered medium-power.

They are also inappropriate to use in stock Ruger Mini-14s made since 1994 because these rifles use a twist rate that doesn't properly stabilize anything heavier than a 62-grain bullet.


Hopefully, this mini-primer will help the OP figure out what all the fuss is about, machinery-wise.

If nothing else, it will give him a start on his own research.