12.7 x 81 Breda question

My 12.7 x 81 round has the headstamp K23 .5B it is semi rimmed and has a nickel jacket spitzer bullet ,flat brass primer with Blue seal, all the arrows point to a Kynoch Incendiary round made in 1923 I guess for export to someone, now Huon on page 211 states this round was not developed until the 30’s,and derived from the 50 Vickers, the 50 Vickers however WAS developed in 1923 as a rimless round ,so what do I have ? , a very early 12.7, or was the 12.7 developed earlier than the 30’s or maybe a Trials or experimental round ? Thanks Randy

I have a semi-rimmed one headstamped K23 as well. It is clear that Vickers developed this variant for export purposes in parallel with the rimless British one (their designation was V/565 compared with V/580 for the rimless one). However, it may not have been made in Italy until the 1930s, which would account for Huon’s statement; the Italians (and later the Japanese) did of course develop their own loadings including HE shells.

There’s an illustrated history of the .5" Vickers guns and ammunition on my website here: quarry.nildram.co.uk/Vickers.html

Thye Kynoch design (Export) was bought by Japan in the late 20s (along with a lot of other Kynoch ammo) for trials of various Aircraft armaments, both by the Army and especially the Navy (IJN).

By the late 1930s, italy was supplying Japan with 12,7 Breda design HE-I and tracer; the Breda centrifugal safety fuze was futher “imporved” by the Japanese to make it fully dismountable ( with a special “C” wrench and left hand threaded Fuze cap); By 1941, Japan was using the imported italian ammo fopr combat, and serious production of Japanese made 12,7 started onloy in Late 1941. I have “Mixed belts” of 12,7 from downed Japanese Fighters with a mixture of BPD 37 and 39, along with 1941 and 42 dated Fused Japanese made HEI (cases are not headstamped, but the fuzes cary all the necessary info.). It seems that Italy, up to 1943 at least , continued to supply Japan with 12,7 ammo via cargo submarine from Italy direct (via straights of Gibraltar, the Atlantic, Indian oceans to Singapore, then on to Japan proper.; some supplies did reach Japan after 1943, from Italian cargo subs working out of Betasom, Bordeaux, until mid 1944.

The Japanese also developed, mid war, a contact-HE load, using the two jacket construction with PETN and RDX as the “crushable” explosive charge ( similar to the 7,7 explosive round). THis reduced the costs of HE, as the small fuze of the 12,7 Breda design was very expensive to make, even with Repetition Lathes.

It is sort of poetic justice that because britain forced Kynoch to restrict the .5 Vickers rimless design to British Empire users, and so made the "semi-rim cartridge an export possibility, that the 12,7 Export had a much wider diffusion, especially in Aircraft guns, over the entire world, and was improved into several Versions…whilst the Kynoch rimless version was limited to naval use ( and occasional HMG Ground use, and lost out for aircraft use to such possibilities as the 13,2x99 (Hotchkiss and browning) which was initially considered in the late 30s by the RAF, and then of course to the 12,7x99 BMG cartridge.

Of course the Breda/Japanese cartridge also disappeared after WW II (victim of the .50BMG), but it was a major player in Fighter armamment ( and the Italians used it alongside the 13,2mm in Land warfare and AA roles.

regards, Doc AV
AV Ballistics.
Doc AV
AV Ballistics.

Thanks very much Tony and Doc, lots of good info, great site Tony, Randy

Not to forget the Hungarian production and the Spanish one which lasted over 1945.