Hi. I found some rifle casings, one of which is shown below, while walking in the scrub, but am unable to identify either the caliber, or its origin. The back of the casing has some peculiar markings. The first one, as you can see below, looks like the Greek lower-case symbol for "tau". For some reason I can't copy/paste it here, but you can see the letter for yourself with a quick google search. The second symbol is a triangle, which is the Greek upper-case symbol for 'Delta' - Δ. It could just be coincidence that they look similar to letters of the Greek alphabet, and they could mean something else entirely. So 'Tau Delta'. I've never heard of this before. The other inscription might be a date stamp: 1909, but that's just a guess. I know very, very little when it comes to any type of cartridge, so please correct me if you think anything I've said here is false.
So, with this information and the two images I posted, do you think you can identify the bullet, manufacturer and year of manufacture?