Help ID unknown (Mauser C-77 ?) cartridge




Vitor: I don’t know caliber the cartridges are, but the cases are shortened and reformed .303 British made by Winchester in 1915. JG


These cases probably found their way to Portugal after WW1. The UK Military didn’t consider the US made .303 ammo satisfactory, and it was relegated to training use. After the war, alot of it was given to Portugal, as well as hundreds of thousands of rounds being dumped in the North Sea.


Assuming that this is a reload of some kind based on the 303 cartridge, what sort of firearm was supposed to use such a load?


When the Portuguese received the W15 ammo from Britain in 1919, they found, over the 1920s, that a lot was unusable, from Neck splits and poor Powder. Portugal had started making .303 ammo in 1922 ( although listed as “modelo 923”) and in about 1927-28, large qauntities of AE cartridges in 7,7mm (.303) utilised salvaged W15 projectiles (double cannelure type, unique to Winchester-made Mark VII projectiles of the W15 contract…the Winchesters were crimped at the mouth, but the Projectiles were also made for loading in Britain, with its “half neck stab crimp” so the extra cannelure…

It seems that by 1927, all the W15 had been declared useless as is, and what could be salvaged was done so.

The cartridge cases were problaly then either scrapped, or maybe recycled, the same way the Dutch used 6,5 cases to make 10,4 Soerabaya Revolver rounds ( same head size, rim as the 6,5x53R ) Just luckily, the .303 case is also similar to one of the 10,4 cartridges that Portugal may have used in revolvers of the Abadie Type ( Chambers very similar to a .44 Special in US terminology);
So a Logical conclusion, is that Lots of suitable Wincheserter .303 cases were trimmed of all “cracked” neck and shoulder, and maybe even “neck reamed” to take a .420-425 lead bullet suitable of a 10,4 type revolver.
BTW, even though the Original W15 case necks and maybe Powder was defective, the primers were OK, at least in the 1920s…I have tested some W15 ammo back in the 1970s, and except for the cracked necks, it fired efficiently.

Now, since all the records of FNM ( successors of AE) have been destroyed back in 2005, when the factory was closed and demolished, we will never know for sure what was the sequence of events…but I think my “suppositions” may hold water.

BTW, I have done a full analysis of AE .303 cartridges from 1922 to 1937, examining Bullet weight, design, powder type and charge, primer design and Berdan Pocket design, from hundreds of examples ( veterans of Lorenco Marques, via Century Arms and a dealer in Australia…several Mixed Portuguese crates of the stuff.) I will have to dig up the original, type written analysis I did back in about 1980-82, when I acquired the ammo (it had a lot of W15, RA 16, USCo.17 and RL 17 Z and other British “z” loads etc. as well, but NO British Cordite ammo. And one of the Portuguese Cartons ( steel strip re-inforced edges) was marked “Cartucho 7mm.7 M.919” ( and not the later “M923” found on the Crates.)

So the “M919” must have referred specifically to the Imported US Contract and other Nitrocellulose ammo, whilst the “M923” referred to the In-country made AE ammunition.
AE ceased manufacture of 303 in about 1937, when RWS retooled the factory for 7,9mm ammo (M937), and FNM took up manufacture again in about 1948 or 49, and continued throughout the Colonial Wars (Portugal still had .303 calibre MGs for aircraft use, and some Bren Guns etc, in its colonies, even though the majority of new equipment since 1937 was in 7,9mm, until they adopted Nato 7,62…they even bought New FN BMGs in 1949 or so, in 7,9mm. All the pre-1937 Lewis and Vickers guns were either converted to 7,9mm, or disposed off.

Getting back to the “cartridge” shown, see if it will fit a Portuguese Abadie revolver…originally a black powder, round nosed lead cartridge.

Obrigado, Vitor, for showing us this rarity.

Doc AV,
AV Ballistics.
Brisbane, Australia.


DocAV, I must say that I am amazed by your vast knowledge on Portuguese ammunition industry!



Victor - unfortunately, you do not give all measurements of the cartridge, such as rim diameter, base diameter, case mouth diameter. I know this is from a standard .303 case, but since the case has been altered, it is important to know how much. It does not appear that the rim has ever been turned down, but the with the age of it, it cannot be told just from the picture if the base has been reduced.

As is, except for the overall cartridge length which would preclude use in a Winchester 73 rifle and perhaps also in a Model 1892 Winchester, the cartridge, based on my measurements of an original “W 16” .303, might work in a .44-40 (.44 WCF) caliber weapon, expecially a revolver where the short OAL would not cause a jam due to one cartridge and a portion of the base of the next one in the magazine tube feeding onto the carrier and jamming the rifle. For 1873 Winchesters especially, overall length of a .44-40 cartridge is somewhat critical.

I cannot say I am right. I can say that it is not important that the cartridge doesn’t have a bottle-neck like the .44-40. Some new .44-40 brass sold is quite straight, and works just fine, forming the bottle neck on the first firing.

The measurements are not perfect, but in the main, they are smaller than a .44-40, although the .303 rim, measured on my Winchester round at 13.33m/m as opposed to 13.16m/m on a Starline, oft-fired case, might be problematical. That’s why it is important to know the rim diameter as it currently is on your cartridge. Still, Erlmeier Brandt shows .44-40 rim diameters as big as 13.40m/m on .44-40, so it might NOT be a problem. The head of the Winchester 16 .303 is 11.42, and again, on a fired starline .44-40 case it measures 11.78. Not ideal but considering the thick web of a .303 round, probably usable as improvised munitions.

Just a guess. There really isn’t enough information for any more than that, I think.

Edited to correct a caliber designation.


The rim diameter is .525