I am not really at home in this scale but the only ammo sets I could find were the Cyber Hobby sets for the 105mm and 75mm fieldguns/howitzers. Though very nice (and expensive) they are either too big or too small ( and have a straight cartridge case instead of a tapered one).
For the casings or cartridges I was thinking of cutting down rifle cartridges. Some of the older types have rims and are tapered like the .303 or the russian 7.62x54R (Mosin Nagant). Both are however too small, ending up at 12mm OD or 1/1 : 72mm instead of 88mm. The best fit would be the Snider .577 but these are extremely rare (1853!, though there are recently manufactured rounds available by Ten-X).
There also should be 24 gauge full brass shotgun shells around though I have not yet found a source for these ( these have however a straight case). Incidentily reloaders often convert 24 gauge cartridges to .577 Snider cases! Does anyone have access to these shotgun cartridges? Our American breathern are a bit reluctand to ship these cartridge cases......
Both cartridges and shells also have distinctive storage boxes: C206 for 8 cartridges, P59 for 4 HE/smoke shells and P60 for 4 AP shells. There should also have been a wooden box for the fuses. The boxes would be ideal to print on a 3D printer, does anyone have 3d scans of these boxes? I have seen them somewhere but cannot find them anymore.....
Could have been at a site that also makes 1/35 accessories.
Cheers,
Marcus