All right, this is sort of a new school tech question, but I'm really frustrated.

I'm putting together a Fly Pantera II frame--my first press fit frame--and I'm trying to get a Spanish Primo BB in it. But the d*mned thing won't press in all the way. Either bearing is sticking out around 1/8". I measured the shell, and it is indeed 68mm, which is what it should be...meaning the bearings should fit flush to the frame. I greased them up a bit, and started cranking them in w/a bearing press, and they bottomed out. I tried a hammer and a bench vice after that, but clearly they won't go in any further.

I supposed I can ride the bike like this, as they're in there solidly, and it's a floating BB, but it just looks shady as all get out. Does anyone have any suggestions? Are Fly frames known for being a pain in the *** on this count?

I just saw a video in which Jim C presses a Mid BB into a Sunday Wave II frame, in which the BB shell is machined for tolerance after welding. It takes like 10 seconds. As for me, I'm losing my mind.

Get out the calipers, I bet your spacer/sleeve that you put in between the bearings is too long.

^^^
either that, if so shave it down a tad.

BUT, I highly suspect it's as it should be, as supposedly heard primo spanish and I think mid bb bearings overhang out a tad, if it's only about 2-3mm I believe you have it right.
My mate has a failure spanish bb and new primo hollowbites, same deal again, overangs 2mm roughly, just how it sits.

Especially if your using a press, it'll be one of 2 problems, unless theres a build up of paint or some [I tried to curse] on the lip in the shell, have you checked that?
Ok, pull it apart
Measure everything up
Find where everything should sit, (so you know what it'll look like, and don't cut until you have Checked the bearing seating position.)
Identify whats wrong, (if anything)
Alter if need be

THEN try the press.