"In the real world of service life Armourers would simply file the old number off, clean up, make good, send through the parkerizing process and re-use. Same as many other numbered items being re-used. Waste not, want not and all that."
And there we have the essence of the problem with the "numbers game". Presumably (correct me if I am wrong) a service armorer did not renumber non-pressure bearing parts, as these were irrelevant for safety and did not invalidate the proof.
But readers should ask themselves: why are people keen on acquiring unnumbered parts?
Maybe it is just my cynical attitude to such matters, but the thought inevitably crosses the mind that it is because in many cases they want to stamp on a number to match their rifle.
The number itself is irrelevant to the functionality, but does - oh what a surprise - increases the value to a future purchaser when the rifle is sold as being "correctly" numbered. In fact, the whole setup is no longer correct, but the falsification of the part by forging the number (i.e. imitation of an original "documentation of origin" that was intended to prove to which rifle the part belonged) has now created a fake from the aspect of "originality".
Questioned, I have little doubt that all those responsible would reply with one or both of the following well-worn and specious arguments:
a) "Of course I know that it is non-original to that rifle and would inform any prospective purchaser/leave a note in the butt trap." That is IMHO no better as an excuse than an art forger who sells his fakes to a dealer who knows that they are fake. But when the purchaser/dealer resells the item?
b) "Of course, any expert can tell that it is not original". What is that supposed to mean? That it is OK to defraud non-experts?
I feel a prophet in the wilderness when I write: stamping of numbers onto parts by a non-authorized agency is fundamentally fraudulent.
Yes, I know it's a bee in my bonnet, but perhaps it might make a few people think.