I once (1970s) passed up a double-set trigger octagon barrel German 8mm Mauser with leaf sights and nice wood in perfect condition for $80! Later I let a Savage 24 in .357 mag/20ga get away, I didn't want to pay $300.
I'm a big fan of the 30/06. Make plinker practice loads for it with 1/2 case of Buffalo Rifle (Trail Boss if you can afford it, the old 13 Red Dot works too) and whatever .308 junk bullets and primers you have laying around and develop a good full strength hunting load in the bullet weight you...
I like to start with crimped factory loads that will live in the magazine most of the time and sight in with those- "cold gun", because it's the first shot that counts. I hunt elk- often in the timber- so that's a 30/06 with 180/220 or 7mm mag with 175 grain bullets. Then I try to make accurate...
Autos and rimfires only. Especially pistols. Too inaccurate, too expensive to shoot, hard to reload for, not enough fun. Other people like them, let them have them.
My opinion about the 20 gauge for kids is that reloading light is even more important than it is for a 12 because I've seen men buy kids lightweight, cheap pump shotguns and they don't realize with factory ammo that kid is getting more recoil from that 20 than he's getting in his heavy, long 12...
If you're a reloader (which you probably are or you wouldn't be on this site) get the kid a light-weight .308 or a 30/06 (my preference, because there's more room for fingers in the magazine) and make a bucket of low recoil ammo with 110 "plinkers" (M1 carbine bullets, very cheap) that hit in...
The more you shoot, the more recoil sensitive you get. I had an old friend who killed a bull elk and a big whitetail buck every year and his two guns were a .303 Savage 99 and a .270 Win. Mod 70. He'd ask me to check his zero for him, because he felt doing so himself might spoil his shooting. He...