Introduction. The study of the history of Russian grenade manufacturing, combined with the exhibition of researched specimens in museums and the provision of opportunities to create their replicas (for example, for subsequent use in historical films and reenactments), contributes to the popularization of Russia's military-technical heritage. The objective of this study is to describe three types of hand grenades of previously unknown design, discovered in St. Petersburg, and to determine their place within the overall history of hand grenade development in Russia. The relevance of this research is determined by the fact that examining early 20th century hand grenades and drawing comparative analogies provides insight into the evolution of military-engineering thought among Russian engineers in what was then an emerging field of military technology. Methods and Materials. This study was prompted by discoveries made between 2016 and 2025 in St. Petersburg and Kronstadt, near abandoned artillery laboratories and warehouses. In total, approximately three hundred grenade bodies of three distinct types were found, a small portion of which were in good condition. None of the discovered grenades contained explosive fillers, representing ready-made safe mock-ups. Literary sources from the early 20th century and contemporary scholarly works in the relevant field were examined. The research is grounded in general scientific methods and specialized historical methods (typological and historical-comparative). Results and Discussion. Morphological and technical analysis of the grenades under study revealed their probable manufacturing technology, operational mechanism, and most likely origin. A date range of 1912–1914 has been proposed. It has been established that these new historical sources can be considered previously unknown links in the chain of designs illustrating the evolution of engineering thought from the N. S. Lishin Mk. II grenade to the 1914 V. F. Stender grenade; the objects themselves may be designated the "Early Model Stender Hand Grenade," with three distinct types identified. Conclusion. The results of this work will enable future researchers to correctly identify archival records concerning the design, production, testing, and use of the studied grenades. Furthermore, they will allow a broad readership to become acquainted with the unconventional design of early 20th century Russian hand grenades.