IBTL means In Before The Lock - as this thread should and likely will be locked for various rules and code of conduct violations on your part and mine as well for inquiring about your knowledge. First on your part is hijacking someone elses sales thread. The second is making comments that could be percieved as personal attacks. See your quote below.
I think it's right in his name - 'forgery'
I did so for two reasons only - first the item was already sold, so my comments will have no impact on the sale - second - you had already hijacked the thread, so I jumped along for the ride.
Luckily this item sold before you came along and potentially cost this guy a sale.
Below is a poor picture, but it is a picture of a barrel I had with the stamping "FNMI MP 5.56 NATO 1/7". It was not some home grown stamping or etching, it was actual manufacturing marks like you would see on Colt barrels and other. I am sorry that I sold this, as it it a very high quality barrel, so I am looking for another. In my search, the last thing I need to see is some uninformed person spreading misinformation, disinformation and wrong information the product I am looking for.
My advice is this: If you have a problem with the way people list their items, contact them directly and ask for pictures and proof, like the rest of us do. Don't hijack their threads and cost them sales and don't waste other shoppers time.
While you are correct with your description of people calling anything that they don't know who made as "FN", take up your issue with ebay sellers in the proper forum. Maybe while you are there you might learn a couple things about the topics you were talking about. This topic is broached in the discussion forums many times and a running joke about the topic goes something like this - "I don't know who FN made it".
Finally, with 100+ posts to date, you seem to have been here for awhile. Why don't you pony up the cash for a team membership and help the people that run this site out.