It is not necessary to make it available. Gun bunnies can look at the long list of firearms, build their dream gun, and stat it reasonably already.
I don't think the "Spycraft Weapon Damage Formula" will be made available.Don't think it should, either.
I was suggesting it be included if
(and only if) the ruleset is reduced to the sort of thing what it was in the SEH (which seems like a real possibility, just from what I've seen Pat and Alex say on the subject - that they have largely heard back that the gun list is too long, and players don't want pages and pages of kit).
If we get a 3.0 Modern Arms Guide (which I would very
happily buy), it won't be an issue. But if we get a single page of guns, rather then having guns of virtually every caliber and design to reverse engineer from, the gear heads out there will need some way to figure out rules for their weapon of choice (importantly including the gear head GMs who want accurate stats for the weapons an organisation use in real life).