The secret to the custom mags is RIT dye. Available at most grocery stores in the laundry detergent isle. Pic your color then follow the following instructions:
Take a 2 quart pot with about 1 to 1 1/2 qtrs of water and bring it just to a boil.
Add one table spoons of RIT dye and one table spoon of salt.
Remove pot from heat and add your disassembled plastic parts.
Takes about 4-5 minute for color to soak in. Check progress as you go. Long time equals darker color. Rinse parts with water and dry. You can re-dye the part if they are not as dark as you want.
FYI, this dye will add color to a white sink. Be sure your wife is not home and that you have bleach on hand to clean up the mess.
As far as barrels go, the more expensive the better the barrel. Shilen, Volquartsen, Green Mountain, ER Shaw, Tactical Solutions are all great barrels. ($$$) Cheaper barrels (Shooters Ridge, Butler Creek) are OK but not known for significant improvements over factory barrels when it comes to accuracy improvement.
FYI, my barrel is a Green Mountain Areo barrel. 16.6" fluted sporter with an aluminum shroud. Cool looking and better then factory but not nearly as accurate as true heavy barrels.
Not to talk down this fine forum but the folks over on at Rimfire Central forum know tons of stuff about "fixing" 10/22's
APEXDUCK