Thinking about a new "tactical" rifle.

That's what LRI uses as loaner rifles for students who need one. Solid. Sub-MOA accurate. Go for it... you wont be disappointed.
Of course there are other options.
Remington has several options.
Savage has some.

Which FN the PBR or the SPR?

I'm assuming you mean "precision" tactical and not spray and pray tactical, in which case I wholeheartedly recommend Remington. I own a Light Tactical that makes me smile each time I pull the trigger. Ogre seems to be loving his new Remington too and I'd love to try one of the M24s in 300 mag or 338 Lapua. Remember that good ammo costs, this is why I don't own a big 50, the cost of feeding it 100 rounds of match grade ammo is equal to the cost of another gun. Get good steel rings and spend at least a couple hundred on the scope too.
Hope I helped.

Define "tactical". Something that looks cool while you're busting prairie dogs or punching paper? or something you'll want to jump out of a plane with? There're IBA M40s and then there are Savage's that will shoot better than 99% of the people who buy them. Like the guys above said, Remington 700s are a great start. A word of warning though, once you start shooting long distance, whether it's "tactical" f-class, palma, whatever, you're in for a fun, challenging ride:-)
So, anyway, what did you want to do with this rifle?

Which FN the PBR or the SPR?

-dirk-pitt

Whoa, if you can spring for the SPR...a late best friend helped design it. Can't go wrong there. Sorry, in the initial query I thought you meant an FAL variant, hence the "purpose" questions.

They were the SPR's at LRI. Shep got a killer great deal on them and snagged a bunch.
It was an impressive rifle. I'd have bought one myself if it was available to me as an option... and at that price, i'd have got a couple.