If you can grab a lightly used 10/22 carbine for a nice price sending it to Randy at CPC should yield great results. He did both of my bolts and I couldn't happier.
This info is from his
website
Customer results at 50 yards: .25 to .56".
RUGER 10/22 FULL TUNE-UP LR, includes 3 items:
TRIGGER JOB
2.0 - 2.4 lb trigger pull
Trigger and hammer side shims
Trigger overtravel screw
Forward anti-creep/slack screw
Auto-bolt release conversion
Single stage pull reworked to be as crisp as possible
Oversize receiver pins installed to tighten trigger group
Extended magazine release installed
BARREL SETBACK & CROWN
CPC will accurize aftermarket barrels, bull or sporter. Examples - Clark, Midway, A&B, Butler Creek, Houge, Shilen, Ruger T, Green Mountain, Kimber, Whistle Pig, etc, (.22 L.R. or .17 HM2). Stainless or Blue
Ends of blued barrels are re-cold blued
Setback breech end by .187 to .250". Shorten chamber, recut barrel shank oversize to fit receiver hole perfectly
CPC semi-auto match freebore chamber reams until a Winchester Power Point, Eley, or CCI bullet lightly sticks. These are used as gauges since all .22 L.R.s will work except some longer .22 Hyper-velocity's.
Chamber polish
Recut extractor groove
Fit new spacer into barrel's lock cut
Cut new 11° recessed target crown
Stone slide area in receiver
Recut and square .920 dia. c'bore on receiver face
BOLT COMBO (see 10/22 Bolt Work for more details and pictures)
Bolt is totally disassembled, cleaned, deburred
Bolt face is surface ground and squared to .0425" LR rim headspace depth; same as bolt action rifle for accuracy and reduced flyers
Bolt side is beautifully prism jeweled
A hole is E.D.M.'ed and a stainless dowel pin pressed in over the front of the firing pin to hold it from raising up, reducing flyers and to get more consistent firing pin strikes.