You nailed it at the end.
If you roll the clock back 10-15 years, it would be a fine bet that Federal ammo used Federal primers. These days, however, you have (at minimum!) a 50% chance of even getting "Federal" ammo in the Federal branded packaging.
I'm sure that Federal/Speer/ATK has details about it, I don't know if they are available, but some of the Federal ammo out there is merely headstamped as such and is being spit out of the same machines (and likely the same production line) as the CCI/Speer/Blazer Brass product. This can be seen easily with the extruded 9mm brass -- and can be compared to the other, FC headstamped non-extruded 9mm brass. Easily seen in .45 also.
Being that I don't use Federal primers, and I've only once briefly used them back in the 90's, I'm in no position to comment on how those primers may have changed (or not) over the years due to ATK's holdings and influence.
It's starting to look like you are attempting to squeeze blood from a turnip here in this thread. Why don't you buys some primers... online, garage sale, back-alley at 3 am, doesn't matter. Buy some primers, build some loads, shoot some guns and if you make some interesting discovery -- document it and share it here in this thread.
In the mean time, you can always send an e-mail to Ben Amonette at ATK and if he doesn't have the answer or won't share the answers, you'd have to bust in to the joint to get the answers you truly seek.
Attention Brass rats and other reloaders: I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.