I put the OKG-40 (ОКГ-40) Iskra (Искра) under-barrel grenade launcher (UBGL) into the basic history of the GP-25 (ГП-25) Kostër (Костёр) Janes Infantry Weapons (JIW) entry, which I rewrote not long before I left the company; see later comments.
You can find images of the OKG-40 launcher, and its OKV-40 (ОКВ-40) round if you search for either in Russian. The 'O' stands for the Russian word for fragmentation, the K for the Russian word for the shaped charge effect, the V for the Russian word for a round of ammunition, and finally the 40 standing for its nominal diameter in millimetres.
I've never seen any sectioned images of the OKV-40 round, but I'd imagine it's got a conic shaped charge liner and HE fill within the externally scored/embossed warhead section. This warhead section covered by the hollow truncated conic nose at the front and sealed at the back by the rear section.
The rear section, which has the pre-engraved rifling on it, likely holds the propulsion system and at least some if not all of the fuze. The former is likely similar to a VOG-25 round. The latter is likely at least inertia- and probably also spin-armed, whilst being impact inertia-fired. This type of fuze may explain its poor performance on sloped armour mentioned on some webpages on it. Due to these and probably other problems, developed was supposedly stopped in the early 1970s, with 1970 and 1971 are often quoted. Further development of the idea however would result in the GP-25.
Going back to the GP-25 entry,as that was an interesting rewrite due to the decades old boo-boos in it. The entry referred to the GP-25 as the "40 mm BG-15 (БГ-15) Kastyorʼ". Well the former was a mis-transliteration of the weapons GRAU index code of 6G15 (6Г15), which would may have originated from the the Small Arms Survey in the 1980s! The other boo-boo was the mis-transliteration Kostër (Костёр) as 'Kastyor'.
I also found the GP-25 codename referred to online as Mukha (Муха), which is actually the RPG-18's codename.
