An M4 medium tank passes by knocked out PzKpfw. IV medium tanks, St. Lo, France, 9 July 1944. by David C. Hardison Editor’s Note This article is a reprint of BRL Memorandum Report No. 798, published by the Ballistic Research Laboratories (BRL), Aberdeen Proving Ground, Maryland, in June 1954. The report was unclassified on 29 August 1972 under Department of Defense Directive 5200.10 (which actually stipulates that the material was to be downgraded at three year intervals and declassified after twelve years, although such is usually not accomplished until someone actually requests such to be able to utilize or copy the document). I am indebted to Abe Flatau for providing a copy of this report so that it could be reprinted and make it available to all who are interested in such matters. Merriam Press originally published this in book form in 1988 and went through seven editions, the last edition released in 2012 with ISBN 978-1470079062. Abstract A study of some tank eng...