The .455 SL revisited


On the old Forum, there was a long thread concerning the “unknown” headstamp “C” that appears on .455 Webley Self-Loading cartridges, always either a blackened case “ball” round or a dummy. Many will not recall that thread either thru limited interest or joining only the new Forum, so I will review very quickly.

The Headstamp “C.17 I” on this cartridge has been regarded as unknwon. The rounds are odd in that they are loaded with Birmingham Metal and Munitions Co. Ltd. bullets (easily identified by ogive and base marking) and that on the “ball” rounds, the cases are always blackened. I reasoned that the “C” might well stand for “Colt,” since during that period, Colt made the Government Model Pistol for the British in caliber .455 Webley SL. Since that caliber of ammunition was not made in the U.S. Colt would have had to obtain any test material from England. Ball ammunition was not a problem. However, they would have needed proof loads (the proofing was done by British technicians, but at Colt, according to the terms of the contract) and functional dummies. While not a British marking, a backened case was a typical U.S. marking for a proof load, and Colt may have required the American identification marking to avoid any chance of a mishap during testing. Since, again, these “C” rounds only appear as bulleted live cartridges with a blackened case, and as dummies, it is not unreasonable to believe that they were made specifically for Colt, and I still hold that opinion. The blackened-case “C” rounds have a very stiff charge of nitro-cellulose powder, not the normal fine cordite found in .455 of the era. British author and authority Ken Elks reckoned that the charge represented a 50% over-load in pressure.

As to what the “C” means, I was convinced it was “Colt.” However, in researching headstamps for a recent thread about 7.62 x 54R headstamps, I found that the Government factory 1 (normal headstamp “G. F. 1” along with a date) was administered by none other than the Birmingham Metal and Munitions Company Ltd., whose bullets appear in the “C” headstamped .455 Webley auto cartridges. There is also a note by Labbett in his book on the .303 Cartridge that the “G” standing for “Government” often appears as a “C” on headstamps. This comment kind of hit me in the face like a wet rag.

Could the “C” headstamp actually indicate manufacture by Government Factory Number 1, at Blackheath, Staffordshire, which opened in 1916 and was administered by BM&M Ltd.? The coincidence of Labbett’s statement and the fact that the “C” headstamped rounds have a BM&M Ltd. type projectile is hard to ignore.

On the down side, the headstamp is simply “C” and not “C.1” or “C.F.1” on the black-cased, bulleted rounds. However, and this is starting to loom as a very big “however”, the headstamp on the Dummies is “DUMMY C 1 17” with the one not apparing as in a “Mark” number as “I” but rather as just a straight, vertical line. (There is no hook on the figure as this type-face shows. When typing the headstamp I had no way to make a straight vertical line). One of the questions about the dummy was why is was shown as a Mark I (C 1 on the headstamp) when it is not a specific Mark I pattern of dummy. Perhaps that should not be read as “C Mark 1” but rather as C Factory 1"!!?? Note that a similar question was asked about the black case in relation to its being a proof load; that the “I” designation would not be right. Well, I have an Eley military-headstamped proof load, and it too, uses a Mark I ball headstamp, but has a purple stripe across the base and came from the recent house-cleaning of the Birmingham Proof House.

Now I am about 33% each on three choices - Unidentified, period! Colt. government Factory #1.

Any thoughts from our knowledgeable British friends on this? I am sorry to reopen and older thread, but this begs to be discussed for those of us interested in British pistol ammunition.


John, is this what you were looking for?

“DUMMY C l 17”

I used a lower-case L as the striaght vetical line, im surprised you missed that idea.



Thanks, never thought of it. I am an old-time typewriter man, and on some of those, a lower-case “L” has a little curve or wave in it, no dead straight like “l” on this thing. Besides, I did fell off of the paddy wagon yesterday.

Sorry about that EOD my friend - really just a good hearted poke at you in gest. No offense! Come to St. Louis and I will buy you a beer as an apology.

John M.


I seem to remember using a lower case L when I needed to type a headstamp with a vertical line in it before, thats how I remembered it.



You and I have exchanged ideas on the infamous C 17 I round often and have discussed the possible Colt connection at length. I still think this is the most likely explanation, and whilst I can see your logic regarding the possiblity that it means Cartridge Factory 1 I think you are following a red herring.

The origins of the Government Cartridge Factories (GCFs) lie in the requirement for an additional 150 milliion rounds of .303 inch ball per month that had been approved in Spring 1916. Existing UK factories had been developed to the maximum, the American manufacturers had proved unsatisfactory and there were no other external sources.

The government decided to fund a number of new GCFs and approached all the existing manufacturers to manage them. Kynoch declined saying they preferred to expand their existing facilities, Greenwood & Batley never came to fruition, but Birmingham contracted to manage GCF1, Royal Laboratory Woolwich ran GCF2, Kings Norton GCF3 and Eley Bros GCF4.

In July 1916 whilst the factories were stil under construction it was decided to change the production of all of them to 7.62 x 54mm for Russia, as supplies of .303 were sufficient. There were production difficulties at all of the factories and output did not start in earnest until early 1917.

The headstamp used by GCF2 (RL) was the normal R^L headstamp, but the others used a new style of headstamp of “C 17 F x” where x was the factory number, 1,3 or 4. As Peter says, some rounds are certainly “C” and others look more like “G”. Either would make sense as it could stand for either, CF meaning Cartridge Factory or GF meaning Government Factory.

I wrote an article on the British production of 7.62 x 54 in WWI with all the headstamps shown in a recent ECRA Journal.

GCFs 1 and 3 switched to .303 production in early 1918 and used a similar style of headstamp.

The point of this rather long winded ramble is that there was no production at GCF 1 other than 7.62 x 54mm and .303 inch. The official history of the Ministry of Munitions goes into considerable detail about the GCFs, and the above is quite clear. There was sufficient difficulties in 1917 in simply getting the factories up and running without the complication of producing a short run of .455SL.

With regard to the headstamps, the use of “I” with seriphs and “l” seems to be interchangeable, depending on the bunter maker. For example you will find “VII” and “Vll” on .303 ball.

There was no specific Proof Cartridge approved for the ,455 SL, which is not really surprising since relatively very few Webley SL pistols were in service. Certainly in WW2 Enfield were using commercial cases with a purple stripe to identify proof rounds and I am sure the same applied in WWI. The fact that your Eley proof case has a ball headstamp is not unusual. Similarly, whilst the “DUMMY C 17 I” headstamp is unusual, I would not put too much emphasis on this, especially if it was done by Birmingham for Colt.

Remember that the British contract with Colt specifically states that proof ammunition would be supplied by the British Government. Birmingham Metals were already making the .455SL ball round on contract so perhaps they were asked to make the proof and dummy ammo for the Colt contract and marked them in a distinctive way, blackening the cases as per US practice and using “C” as a code.

Overall, I would still class this round as unknown, but with a good chance that it was for the proofing of Colt made .455 M1911 pistols, probably made by BMM Co.

Sorry to be so long winded,


Tony - thanks! You were not long-winded. You did just what I had hoped for, a detailed explanation that would either confirm or shoot down my theory of a third possibility for this headstamp, beyond “Colt” and “Unknown.” We are back to the first two, as you did a good job of showing me why my new theory doesn’t hold water.

My wife is standing next to me, and the smart-aXX just asked how I, of anyone who writes on this Forum, could call anyone else long-winded, anyway. Is there a divorce lawyer on this Forum?

At any rate, not be sarcastic with the thanks! It IS exactly what I was looking for - solid confirmation or solid refutation (is that actually a word?).

John Moss


“Is there a divorce lawyer on this Forum?”

Don’t know.

“refutation (is that actually a word?)”

Yes, a good one.


Glad to be of some little help John. Many of these things are a mystery and it is great fun trying to research the answers.

As for a divorce lawyer, been there, seen that, done it…