Not really. They were shooting innocent people huddled under tables at point blank range with the muzzle of the gun pointed directly at they're faces/body, at that point any firearm/caliber will kill someone or leave them with life altering damages.
Eric originally wrote about obtaining Calicos, like [You must be registered and logged in to see this link.]
mentioned, but they quickly learned they were unobtainable because of the '94 AOW ban that was in place. They both wrote about Uzi's as well.
Any AR15, or AK would have been unobtainable as well at least in they're normal configuration at this time. Both of them probably saw them "unfit" due to how they differed from they're pre-ban configuration (they didn't look like the gats they saw in the movies)...
Also, not very easy to conceal rifles, probably why they strayed away from rifles in general. They sawed-off the shotguns for this exact reason.
I think they just wanted firearms that they could easily conceal, obtain a large amount of ammo/magazines for, all at the same time without blowing they're budget.
"If you could walk a mile in my shoes you'd be crazy too... with nothing to loose." - Tupac