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25 x 181
- Thread starter womble
- Start date
Tony Williams
Well-Known Member
The measurements of the KBB round have been the subject of much confusion. It was for a long time known as the 25 x 184, but no round with these dimensions ever entered production as far as I am aware (although I suppose it could have featured in the development stage).
This cartridge ended up with two different case lengths for different loadings, as explained below (more of my book extracts!)
25 x 173/181 Oerlikon KBB
The 25 x 137's big brother, developed from 1966, uses a lengthened version of the same case in two versions with different neck lengths: 181 mm with Anti-Missile Discarding Sabot (AMDS) and other discarding sabot rounds, and 173 mm for full-calibre TP-T and HE loadings (see photo below). To complicate matters further, this round was for a long time commonly referred to as the 25 x 184; presumably the result of an early error being copied.
Overall round length is 288 mm and weight is 620 g. Combat loadings are:
HEI SD: 230 g hardened steel shell with ballistic cap, contains 20 g Hexal plus incendiary mix; base fuze with self-destruct function; MV 1,160 m/s.
APDS-T: 190 g projectile with 14.5 mm diameter, 156 g tungsten alloy penetrator in a plastic/light alloy sabot; MV 1,285 m/s; penetrates 34mm/60°/1,000m (also AMDS without tracer, and FAPDS; same ballistics).
Although the KBD rotary cannon was developed to fire it, the only service use is in the Oerlikon KBB single-chamber gun, which itself has only been used in a naval CIWS which was purchased only by Turkey. Although it remains in service, it is being gradually replaced and it seems unlikely to enjoy a long future. The ammunition is no longer advertised.
This cartridge ended up with two different case lengths for different loadings, as explained below (more of my book extracts!)
25 x 173/181 Oerlikon KBB
The 25 x 137's big brother, developed from 1966, uses a lengthened version of the same case in two versions with different neck lengths: 181 mm with Anti-Missile Discarding Sabot (AMDS) and other discarding sabot rounds, and 173 mm for full-calibre TP-T and HE loadings (see photo below). To complicate matters further, this round was for a long time commonly referred to as the 25 x 184; presumably the result of an early error being copied.
Overall round length is 288 mm and weight is 620 g. Combat loadings are:
HEI SD: 230 g hardened steel shell with ballistic cap, contains 20 g Hexal plus incendiary mix; base fuze with self-destruct function; MV 1,160 m/s.
APDS-T: 190 g projectile with 14.5 mm diameter, 156 g tungsten alloy penetrator in a plastic/light alloy sabot; MV 1,285 m/s; penetrates 34mm/60°/1,000m (also AMDS without tracer, and FAPDS; same ballistics).
Although the KBD rotary cannon was developed to fire it, the only service use is in the Oerlikon KBB single-chamber gun, which itself has only been used in a naval CIWS which was purchased only by Turkey. Although it remains in service, it is being gradually replaced and it seems unlikely to enjoy a long future. The ammunition is no longer advertised.
Tony Williams
Well-Known Member
Interesting - I can only assume that it was a development round.
Tony Williams
Well-Known Member
Womble, is the date headstamped?
Tony Williams
Well-Known Member
Headstamps aren't really my thing, but IIRC that seems to suggest that the 184 mm case was made in 1996 by BMARC. Which is weird!
BM was indeed a monogram of the British Manufacturing and Research Company (an interesting company). Originally founded as a shadow company for Hispano-Suiza in 1937 and they remained the parent company until 1971. During this period their monogram was BMARC and BMRC GM. In 1971 the parent company was Oerlikon-Bührle who retained ownership until 1988 and the monogram for this period was BM. In 1988 the company was sold to Astra Holdings to become Astra Defence Holdings and the monogram changed to BMO. However, although sold to Astra there were still Oerlikon contracts being executed. In 1992 Astra Defence Holdings went into receivership and what was BMARC was bought by British Aerospace. The Grantham site was sold in 1994. The 2013 ESTC list of manufacturers' monograms still shows BMO as Astra Defence Holdings, although non-extant, details required for possible stocks still retained
TimG
TimG
Last edited:
Tony Williams
Well-Known Member
Thanks Tim, a useful summary.
Tony Williams
Well-Known Member
A brief update on the 25 x 184 - my Swiss friend had not heard of it and is investigating whether it was a purely British development - although heaven knows why!
Womble, you asked another question about a 26 x 116 round, but I can't find the thread - I have never found anything via the Search function on this site, it just comes back with "computer says no" every time - I think it laughs at me! :tinysmile_angry2_t:
Womble, you asked another question about a 26 x 116 round, but I can't find the thread - I have never found anything via the Search function on this site, it just comes back with "computer says no" every time - I think it laughs at me! :tinysmile_angry2_t: