There's been some recent activity around papered bring backs. I've got a thread going on my Nam SKS then I remembered about a couple other rifles that I have that did or likely saw action, but have no documentation.
The first is my MUMed Arisaka T38 with bayo, given to me by my uncle in 1960. He, my Pops, and other relatives were in the 1st Filipino regiment. I never asked about how he came to acquire it, as they never spoke about their combat action when I was a kid. Fast forward to a couple years ago, my uncle at 93, was the eldest surviving relative at a family reunion. At that time he happened to ask me if I still had that Jap rifle he'd given me. I told him I did and it was the most cherished possession in my collection. Since he breeched the subject, I asked him where he came across it. "When we came ashore in New Guinea" was all he said, and I didn't press for more. No papers needed.
FYI, the preferred Filipino method to dispatch the Japs was a bolo.
The second rifle was a Styer M95 carbine that I picked up garage sailing for $50 bucks. The little old lady selling it said it had been her grandpas, he brought back from WWI, and it was broken. The stock was indeed amiss and had been cut just ahead of the front sling swivel??? When I got it back to the barn, I glued it back together and it was good as new. It wasn't until years later that I learned about Dough Boys and duffle cut bring backs. This was obviously one of those. Again, no papers needed for me. PAX