Should this ammo be labled +P?

Energy generally goes up faster because of velocity than bullet weight, which is why a heavier bullet not moving all that much slower can have a lower energy rating, though it is actually a heavier load than the lighter one. That is why an Aguila IQ 65 grain 9mm going 1550 feet per second has an energy rating in the high five hundreds, but a 124 grain going 1200 feet per second has an energy rating in the upper three hundreds, despite weighing twice as much and only giving up somewhere around twenty percent of the velocity of the IQ.

So energy isn't always the most useful factor in load power.

No. They could be using a slower powder which could offset the pressure issue.

Just looked at the page. 1225 feet per second isn't very fast for a 115 grain, the M882 ball is a 124 grain at 1299 feet per second, and it isn't labeled +P though it probably could be.

+P refers to higher peak pressure. IIRC in 9mm, +P is anything from 35,000 psi to 38,000 psi. Anything above that is +P+.

The velocity of the bullet is not taken into account in defining +P.

I think Cor-Bons' +P 115 is rated at 1330 FPS, so the Winchester isn't really all that outstanding, I had always thought 115 standard pressure was faster than the 1100-1150 it usually is, I just didn't know that the +P or +P+ loadings at 1300 gave it *that* much of a boost.

Another variable is the method in which they measured velocity. 1" from the muzzle, 6" from the muzzle, 12" from the muzzle?

Additionally, did their test barrel have polygonal rifling or traditional rifling?

Was the test barrel 4", 6", 12", 16"?

What were the atmospheric conditions at the time of the test?

Also, UMC, WWB, and other cheap ammo generally have a reputation for being on the weak side. Weak ammo is cheaper to make (less powder) and there's less chance of it blowing up someone's vintage (or poorly maintained) gun.

If you think this ammo is too hot for your (presumably modern) firearm, don't shoot it.

I've shot some of that ammo too and still have a box.
It did seem a little hot out of my Kahr but not +P hot.
And personally, I used it for CCW in that Kahr and other guns for years. I'm planning to use the last box as HD ammo as well. There isn't anything wrong with it at all.
If it runs reliably in your gun, use it.