The article offers a critical analysis of some lexical facts in “The Charter of military, cannon and other matters relating to military science” — a monument of the first quarter of the 17th century, which was published in 1777–1781 by V. G. Ruban. The charter was based on a lost copy and was a selective translation of the second volume of L. Fronsperger’s military treatise “Kriegsbuch”. Linguists usually study the vocabulary of the “Charter” based on the printed edition of the 18th century, without taking into account the surviving copies of the monument and its German original. A comparison of the printed “Charter” with its existing copies made it possible to identify discrepancies, including at the lexical level, which could have arisen both during the compilation of the lists and the publication. Such errors led to the appearance of pseudo-hapaxes (such as gasar, koshoda, perinkavus) and hapaxes (variant opelyment), as well as unreliable lexical facts, apparently appearing in the “Charter” as a result of an incorrect reading of the handwritten text (such as aksis, ambrazura, variant iglorit). Consequently, the text of the printed edition of the “Charter” must be used in linguistic research in conjunction with the material of the existing lists of the monument, as well as the German original.