Defense Industries .303?


The one on the left has a GMCS bullet up front and the one on the right a cupro nickel clad jacket that does not react to a magnet. The two headstamps are very much alike, so they loaded two different bullets in 1943 cases. The cartridges weigh 383 grains (GMCS) and 388 grains (CN). I am still searching for books on .303 hence my question.


edit: added picture


Soren–The best book on British made .303 that I know of is:

Labbett, Peter. 1988. .303 Inch: A History of the .303 inch Cartridge in British Service. London, U.K… 258p. ISBN: 0-9512922-0-X

There is also a 5 volume set of 6 x 8 inch paperbacks that cover British Commonwealth, not just Great Britain.

Temple, Barry A… 1986-1988. Identification Manual on the .303 British Service Cartridge. 5 vols. Temple. Burbank, Australia.

No 1 - Ball Cartridges. 84p. ISBN: 0959667725.

No 2 - Blank Cartridges. 95p. ISBN: 0959667733

No 3 - Special Purpose Cartridges. 82p. ISBN: 0959667741

No 4 - Dummy Cartridges [1]. 84p. ISBN: 0959667725.

No 5 - Dummy Cartridges [2]. 78p. ISBN: 0959667725.


Note that the Labbett book is no help in Canadian and other Commonwealth .303 cartridges; Indian ammunition is given some coverage. Jack


TonyE is usually the best source for anything .303 related. He’s not always around so you might want to send him a PM


No, I am here! Now fully retired so no more regular trips to Europe for work, which not only means I am around but also have more time to write for the Journal. The first two articles are about finished.

Defense Industries loaded just about every variant of bullet envelope except CNCS ( but it may just be I do not have one). CN (non magnetic) was loaded every year, and I have GMCS (magnetic) in 1943 and 1945, plus GM (non magneric) in 1944 as well. CN seems to have been used exclusively up until 1942 with mixed materials coming into use in 1943.

Peter’s book is the bible on British .303 but it is out of print and copies are getting hard to find and expensive. You missed one at the last SLICS auction that went to Falcon for a very reasonable $90. There is one for sale at the moment on Specialist Auctions for $300 but I personally would avoid that seller.

If I may be immodest, my own more humble effort on .303 identification is available and covers all British military .303 made in the UK, Commonwealth and United States.



The year of 1943 ( roughly speaking) is the point in World War II where several changes were decided or implemented regarding .303, throughout the Empire, although not all happened at the same dates.

  1. The change from CN or CNCS jackets to either GMCS or GM jackets.

  2. The change from mid-neck stab crimps to Mouth segmental crimps, with similar change in position of the bullet cannelure, from low down the mid bullet body;

  3. The change over from the Four-digit year ( distinguishing “Air Service” ammo) to the simple two digit date for all Services ( although some 4 digit lots were still made in 1945, for Greece etc);

  4. The change of “VII” to “7” in the headstamp;

  5. The Use of Tin Spamcans (Rip-top ammo tins)( 250-300 rounds, clipped and in bandoleers) for Combat use rather than the earlier Wooden Chests of large capacity—as well as the use of Steel chests rather than wood for field use, although wood chests continued until exhausted, and some countries never abandoned them.

  6. The introduction of pre-filled Stripless Vickers belts in rip-top cans, “Ready to use”.

All these changes actually cover the period 1942-44, as their implementation was achieved in different countries at different times.

Doc AV
AV Ballistics.


I think that roman-to-arabic numeral business dates to 1945, about when the Spitfire Mk.21 followed the Mk.XIX. Jack