Assault rifles aren’t high power rifles, in the general vernacular.
By definition you are correct. So apart from the pictures of officers with ‘assault rifles’ what ‘high powered rifles’ were used?
I looked up “high powered rifle” and there’s no agreement as to what it means, except “not a .22 rimfire rifle.”
Yeah, I would tend to agree, you do not think of that when you hear the phrase. However, they are classed as “high power rifles” for competitive shooting, so I think technically you could call them that. Probably one of those instances where technically it is correct, but in general usage it would be confusing.