Ruger 556. Make sure to get the 556 rather than the 223, since the 556 can and will shoot the .223 ammo just fine, while the 223 is not going to handle the 5.56. They are NOT the same.
So neighbor has the Ruger 556, which can be obtained for basically $600, give or take. I think a good scope is also necessary, and that is going to run another $289. I would recommend searching for a scope with a company called Primary Arms. Something like this will work:
https://www.primaryarms.com/primary...-gen-3-illuminated-acss-5.56-5.45-308-reticle
The Ruger has a platform basically made to handle the scope, easy as pie to mount. Literally, takes about 30 seconds to mount the scope.
Go to this site for affordable 5.56 ammo, though the stupid effing Covid panic has made 5.56 and .223 tougher to get. Primary Arms also has a very good selection of ammo, with better delivery prices, but their ammo stock has been HAMMERED by Covid. Anyway, where neighbor gets ammo:
https://www.luckygunner.com/rifle/5.56x45-ammo
You can get 5.56 ammo, 55 grain most common, for a mere 42 cents per round. Depending on where you live, it can be delivered to your front door in boxes of 1,000 rounds.
Oh, also make sure to get AT LEAST one more magazine, generally at a cost of about $12. Once again, Primary Arms has plenty to choose from. Standard Ruger 556 magazine holds 30 rounds. If you live in a state that thinks ***** hats are an attractive clothing option, you can also find the 10-round magazine at a higher ******* cost than the 30-round magazine, because ***** hats mean stupid liberals running the state.
And I emphasize this information is from my neighbor. I wouldn't know. Guns scare me.