I don't know about waiting until 21 to go to the range (via a CHL), but the only thing that's banned is the 7.62x39 cartridge and any rifle that fires it. I have been to plenty CT firearms stores, including one last month, and they had everything for sale: AK rifles in .223 or 5.45, AR-15 rifles, semi-auto shotguns, high-cap pistols and mags, et cetera. Get your CHL and you can buy with impunity, no waiting periods either.
It may suck if you're under 21 but that can't last forever.
I'd have to say that once you get to 21 it's much better than Massachusetts.