Your quite welcome.
When in 58....that is a very hard question to answer apart from saying late.
The problem being all the sellers out there selling guns in wrong boxes with wrong parts and papers. I have trouble sometimes telling right from wrong, I dont know how your guys do it... Look on gunbroker any day and you will find "bitsa" model 41s and not just one, makes any kind research extremely difficult.
Considering 12XXX would be south of mid 1958 I would guess and say it did not come with a false muzzle, guess being a key word here. I think your gun just missed out receiving a false muzzle in the box. A few thousand higher and my guess would not have been the same.