I have firelapped numerous rifles and revolvers. All of mine were firelapped with the expressed intention of shooting cast bullets from them when I was done. It was used to smooth out constrictions and roughness in the bore. I used very slow moving cast bullets (500fps) impregnated with 320 grit from Beartooth bullets. This has the desired affect of smoothing not only the lands, but the grooves as well. This is somethiing not accomplished by jacketed firelapping. If done right, it accurizes your bore and gives you the tapered bore sought after for cast bullet shooting. Accuracy also increased an average of about 35%. All of my firelapped guns are either Marlin leverguns or Ruger revolvers. Marshall Stanton has a book offered over on the sight with alot of helpful information concerning the procedure.