I have a couple of British documents giving a few details of the experimental "3.7 cm Ger. 341 and Fledermaus".

These include the following: the 3,7 cm Flak 341 was a Navy AA gun by Rheinmetall-Borsig; the gun weighed 450 kg and fired at 240 rpm. The 3,7 cm Flak Fledermaus was by "Gustl./Stübg" (Gustloff/Stübgen?) also for the Navy, also weighed 450 kg and fired at 270 rpm. I presume that the Flak 341 and Fledermaus were rivals for the same contract, and fired the same ammo.

A separate document states that the cartridge case length was 290 mm, overall length 425 mm, case weight (steel) 975 g, C/32 mech. primer, "M.Gr." projectile weighing 725-740 g containing 125-138 g HTA explosive, fitted with Lh 12 tracer. Muzzle velocity was 1,000 m/s. The cartridge was therefore longer and more powerful than the usual 37 x 263B Flak round.

Does anyone know anything more about these guns and their ammunition - especially dimensions and illustrations. I presume that the case was belted?