Agree.
So, these few takedown rifles we've seen under 70.xxx might represent early examples - or they might represent rifles that were made 6 months after the 70.xxx's rifles. Without seeing dates in the ledgers, it's almost impossible to tell.
But after looking into the introduction of the 22HP, the introduction of the 250-3000, the first full threaded barrels, and the start of the 99H carbine... every one of them have lower serial number rifles that were accepted from the factory after those things went into production. So.. never say never.