Congrats on your new rig. I have the exact same AP4 with rear sight also, only my FFT has vent-cuts or slots. Chamber polishing I would not worry about, as that usually is an issue with Stainless Steel barrels. Decent Scope for under $500? Either a Vortex Viper PST 2.5-10 or something Weaver or Bushnell. I hear that the Weaver Tactical Grand Slam is a fully Made in Japan scope, with Mrad adjustments for $299. But, the Burris MTAC 3-10 with Gen. 2 Mildot reticle and Mil adjustments has really piqued my interest. If you really want to keep firmly under $500, go with the Burris. The Gen 2 reticle makes holdovers easier with the 1/2 mil subtensions. http://www.opticsplanet.com/burris-3-5-10x-42mm-mtac-g2b-mil-dot-reticle-rifle-scope.html