I'd be willing to bet that FN only has "cold hammer forged" barrel making facilities for the production of their other guns, so that's what they use. They probably run a certain number of barrels through a stress-relieving program, and pick out the best ones.
As for "1/2MOA" maybe the specials that the FBI got to test did that, but the FN marketing brochure says 1MOA.
Cold hammer forging "work hardens" the steel as it is forged, so these kinds of barrels are harder than other types, and might last somewhat longer because of that.
There is no "accuracy improvment" coming from a hammer forged barrel.
Regarding "European hunting rifles using them", hunting rifles are typically meant for one or two shots max, at any particular time. The stresses that might cause shot-walking or other problems are not a cause for concern in that application. Most hunting rifles are not free floated either.
The Winchester Model 70 action(FN SPR) is a basic derivation of the old Mauser action, which is a pretty good action. But it is not particularly well-known for accuracy by today's standards, and nobody really uses that action for serious target work, although I have an old Mauser as a target rifle that shoots good. Cold hammer forged barrels are not generally used for target work either. I know that Steyr SSG rifles use it, and once a friend of mine kept telling me how his expensive Steyr would trounce my stock Remington, and when it came down to measuring groups, the Remington kicked the Steyr's ass. Same with the vaunted HK PSG. I had an M1A SM that could toast any PSG around. They aren't that great.
It's a good big game rifle. Reliable, and reasonably accurate. Very popular with hunters. It was around for a long time and nobody ever really gave it creedence as a sniper rifle, except that there were some VietNam era snipers that did use them, and they worked well. They can be made to shoot good. After the M40A1 and M24, it was pretty well known that the Remmy was a better platform. The chances of seeing an FN SPR at a benchrest match is about zero. There will be plenty of model 700 Remington actions there, at various stages of modification.
There is nothing "inherently wrong" with a SPR or a cold hammer forged barrel that does what it is supposed to do, well. It can be done. As a general rule, it is not going to unseat Remington from the top of the heap in target production-rifle actions, or cut-rifling as the pinnacle of barrel making.
If you have a nice shooting SPR, that's great, and I'm not here to "throw cold water" on anybody's rifle. It's just that "cold hammer forging" is not something that makes it any better, with the possible exception of barrel wear.