I am not sure I could say for a fact those are replicas. All the signs
teecrooz mentions are 100% true but I think it is a possibility they are different as first run parts included since a war was going on.
Back in early 2018, I was missing only a real booster to complete my build. I emailed Spitfire and asked if they would be willing to sell me just a booster from a complete .303 Browning they had listed for sale on their website. A guy named Graham replied within a few days and told me that under no circumstance would he sell me any part separate from the complete gun.
Anxious and desperate to complete my build, I replied and told him that I would be willing to pay him half of the total guns cost just for the booster. Of course he reconsidered his stance and agreed to sell it to me. Once received, I asked that if he stumbled across another to contact me so I could purchase and that I would pay him the same price as before.
Fast forward to the summer of 2018, he emails me this:
My theory is Graham had no clue as to why I wanted the booster when I originally contacted him in early 2018. I made sure not to disclose what I intended to use it for. For all he knew, I was a military collector of sorts.
He and whoever helped him manufacture this hideous replica at the time probably thought there was a niche market for repos and functionality mattered over its aesthetics. He obviously didn’t know that much nicer looking replicas existed for way cheaper.
I know that multiple people in our community have reached out to Graham since I purchased my original booster, and I have no doubt he caught onto why so many people wanted such an obscure part and were willing to pay crazy high prices.
Again, this is just a theory, but my guess is that once he found out what people were using these boosters for, he and his manufacturer went back to the drawing board and produced a much more accurate replica and attempted to pass them along as genuine.