In case of shot by bullet from a revolver, the presence of singeing of hair and charring of skin indicated a distance of:

Close shot is applied when the victim is within the range of flame, i.e., 5-8 cm. The entrance wound is circular with inveed edges, but the rebounding gases may level up or even eve the margins. The skin is burnt with singeing of the hair. The skin surrounding the skin is hyperaemic and shows some bruising, burning, blackening and tattooing. If the discharge occurs at the distance of about 15 cm., the lacerating and burning effects of gases are usually lost due to the dispersion cooling of the gases before they reach the skin. Ref: The Essentials of Forensic Medicine and Toxicology by KS Narayan Reddy, 27th edition, Page 195-196.