Acceptible for mid-1st century?

[Gaius Colletti]

However, wasn't it common for legion recruits to be issued used equipment that had been in service for decades prior?

Yes, but that is really stretching it. You are talking about a helmet that dates as early to the beginning of Augustus' reign. I'm not saying it is impossible, but we don't have any evidence to assume the helmet lasted for 100 years. These helmets were already aging in the early First Century, and newer and more attractive/decorative helmets were well on the rise