One of the most interesting ancient artefacts are the lead sling bullets, especially if they have images or inscriptions. The current paper presents a very interesting lead sling bullet, originating from southwest Bulgaria (found somewhere between the villages of Ilindentsi and Gorna Gradeshnitsa, Blagoevgrad district) that was photographed in a private collection in Blagoevgrad some years ago. The lead sling bullet is almond-shaped and is much larger than the known standard sling bullets. The size and weight of this sling bullet puts it among the largest examples of such bullets that are generally rare. Only a few other items similar in size were previously known from Bulgaria, none of which, however, has inscriptions or symbols. It is particularly interesting that the sling bullet discussed here has a surviving ‘ central branch’ and uncut casting residues, i.e. it looks exactly as it was taken out of the mold. Right in the middle of the side depicting a relief thunderbolt, the Greek letters ΦΙ are visible. They are commonly found on bronze coins of Philip V as an abbreviation of his name with only the first two letters. Many numismatics examples define this lead sling bullet categorically as belonging to the Macedonian king Philip V (221–179 BC) and associate it with the campaign of this Macedonian king in the land of the Thracian tribe Maedi and the siege of their settlement Petra in 181 BC, (Livy XL, 22). The artefact discussed here underlines the important role of the sling bullets utilized by the army in the Hellenistic period. If inscribed, these objects can serve as primary sources of information for the reconstruction of some historical events.