Re: 10/22 barrel replacement
The KID starts as a Lothar Walther blank just like Jim Clark's, and Volquartsens; the bore is lapped to a .001-.002" taper.
With good ammo these shoot easily under 1/2" @50yd, often spectacularly better. About as good as you can get.
When they ran a special last year for $160, I bought three on general principles; my son hasn't regretted it.