Sure, if you can get inside of 40 yards, a shotgun is a great point-defense weapon. You put more muzzle velocity and bigger pellets coming out of it, so you can reach further, well, that gets back to square one.

It's not all that much fun being downrange from somebody shooting at airborne geese from a blind a couple hundred yards off, I can tell you...

Being downrange of a giant laser is probably not fun either. Seems like a good way to blind people by glancing a metal hand rail.

I'm also suspicious of the range of any laser based technology. Atmosphere seems to attenuate it pretty quick. I remember reading in 2007 on slashdot theoretical solutions that shoot some kind of hollow cylinder shaped beam that ionizes the air in the hollow center, allowing a laser to go further before being attenuated.

They must have made some physical advancements far beyond my reading, since birdshot just seems easier.

The range of a 12 gauge shotgun with a sabot round is claimed to be up to 200 yards. The maximum firing range of a 20 mm cannon is 4 miles. That's without using depleted uranium (which both harder and denser).