Bio- degradable plastic training round

I have in my collection for some years a German experemental plastic training round made of Bio-degradable plastic hst "7,62 x 51 DAG96L0652"
on 12 and 6 o’clock. Plastic is semi clear, case and bullet made of one piece. Steel head nickel plated primer, no pa. I like this round, stored in a tube in the dark, dry, but the quality of my round going backwards. Plastic going less smooth, less hard and and there coming slits in the case body, especialy where the case head is fixed. The bio-degradably works, even onder the conditions I stored. Thought a higher humidity, light, and bacteri

As it sounds as if your round is going to continue deteriorating unless you do something I would consider painting the entire round with a clear lacquer (such as model makers use) in the hope that this will form a vapour barrier keeping out the air and moisture. It’s only an idea but it might work!

Please could you post a picture before this interesting cartridge is lost for ever. I’m not sure that using a clear lacquer is the best way forward - the solvents in the lacquer may further damage the plastic. I would place the cartridge in glass tube (plastic tubes sometimes leach plastizers for a long period of time). Use silica gel in the tube to minimize moisture (the small packs that come with electronic goods are ideal). Ideally, the air should be displaced with an “inert” gas such as nitrogen or helium, but this is easier said than done.

Dave S

Here is a picture of the ctg.

As Dave suggested, buy a kid baloon, and fill a transparent air tight container with the gas from that baloon.