Eley 0,303" SGP tracer Bullet (drawing)

Happy collecting, Peter

Peter, any idea what the “SPG” might mean?

No idea at all, I’m afraid.

Luckily there are those who know a great deal more than myself, there’s usually an answer out there … somewhere.


I can not find any reference anywhere to what the SPG stands for but the previous tracer was the SPK could it be -

Special Purpose and then the Letter G was used to denote tracers from then on so could be Special Purpose Tracer “G”


Now you have unleashed a whole can of worms…

To the best of my knowledge, no documentation has been unearthed so far to explain the British nomenclature for special pupose rounds such as “Tracer SPG”.

With regard to the suffix/prefix codes (B for incendiary, G for tracer etc.) I am fairly confident that the theory I put forward in my .303 inch headstamp books is more or less correct, i.e. the code was derived from the first letter of the name (e.g. B for Buckingham) but if that was already in use then the last letter was used (e.g. K for Brock as B already used). If both the first and last letter were already used then the second letter was adopted (e.g. L for blank as both B and K were already used).

That is all very well, but it does not explain the “SPG” itself. It is very tempting to assume the explanation that it is “Special Purpose G”, but the previous tracer was the Mark VIIT SPK. That cannot mean “Special Purpose K” because the “K” was the Brock round! Surely if the VIIG SPG was really “Special Purpose G” then the VIIT should have been “SPT”?

When I originally published my thoughts on the full list of codes I said “W” for Armour piercing was unknown, but I am now sure it comes from “Woolwich” to distinguish it from the Kynoch KAP round. Simialrly I listed “Q” for Proof as unknown, but since “P,R,O” and “F” were already used for other types it is possible that they simply took the next letter to “P” in the alphabet and used “Q”.

I think a small prize should be offered for whoever finally finds the documentary proof of the origins of these codes!


I have no rational ideas as to the meaning of the SPG letters but an earlier design of tracer was made by Aerators Ltd. of Edmonton. Aerators were mineral water manufacturers pre-war under the trade mark; “Sparklet”. Their tracer bullets became known as “Sparklet tracers”. Sparklet was then abreviated to SPK by early 1917.

The above information is condensed from the book; .303 inch by P. Labbett and P.J.F. Mead.


Indeed that is so Dave, (and I should have put that in my earlier reply) which is why I made the point that “SPG” cannot mean “Special Purpose G”.

…but unfortunately it does not get us any closer to what SPG actually does mean!


this may be a foolish question but could it relate to the tracer compound? i have no idea what was used in this case or how many different types of trace compound there are…

Not a foolish question at all, but the tracing compound was the same in both rounds. The difference was that the VIIT (SPK) was a solid bronze bullet with a central hole filled with the composition whilst the VIIG (SPG) was constructed in what is now the normal way with a lead forward core and copper container holding the tracer composition.

This was much easier to manufacture and also overcame the difficulties of boring the hole in the VIIT exactly central which compromised accuracy.

The pictures attached are from the hand written approvals ledger of the Woolwich Inspection Department. The first shows clearly that “SPK” was derived from “Sparklet”, but the second gives no indication whatsoever where “SPG” comes from. One would have thought that an improved SPK might have used the next alphabetic letter and been termed “SPL” but it was not so.

In my experience there is always a logic behind British nomenclature, however obscure it may seem, and I would love to know the answer to this one.


interesting, if SP refers to the compound perhaps G refers to the change in bullet construction, does the G in british usage refer to development at radway green or something like that?

SPK was simply a contraction of Sparklet rather than a description of the composition.

Unfortunately G has no such connotations, but nice guess, though this was 1916 and Radway Green did not open until 1940!


thanks, you are very forgiving! i 'll leave to people who know!

How 'bout “Society for the Propagation of the Gospel” - SPG; one of Todhunter’s codes for tracer ammunition. Source: World War I Armaments and the .303 British Cartridge, B.A. Temple.

Being unworldly, (and unworthy) on this subject and having read the previous posts I should keep my views to myself but coming fron a technical background I feel the need to just point out that Sodium gives a strong yellow colour when burnt and Phospher is self explainatory in the context of tracer. Now I am going to back off and stay quiet

TonyE–You said "When I originally published my thoughts on the full list of codes I said “W” for Armour piercing was unknown, but I am now sure it comes from “Woolwich”. You could be correct, but I have always thought the “W” stood for “Wolfram”(Tungsten). The name “wolfram” (or “volfram”), used for example in most European (especially Germanic and Slavic) languages, is derived from the mineral wolframite, and this is also the origin of its chemical symbol, W.

Ron -I think that is a bit of a myth, quite honestly as the Mark VIIW did not have a tungsten core. It was high grade hardened steel from I believe Kayser-Ellis.