Hi Ian, This guy is pretty knowledgeable when it comes to USMC gear, or at least everything he's said in his other videos correlates to what I've read in other places. I've never actually seen a Carlisle pouch that was marked with anything other than US. I think the blank ones you've seen might just have worn off over time. He says that by mid-war the Army depots were supplying everyone. He has a lot of videos on USMC kit and he has one of everything from ww1 on, and sometimes pre ww1.
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