Even though a firearm is rated for +P ammo, I myself wouldn't use it. If I want higher pressure loads, I'll use a magnum. One thing I always look for in any ammo, including defense loads, is accuracy. In my S&W M&P 45, I use Remington Golden Saber 185gr. BJHP (Order # GS45APA), which are NOT +P. Now before anyone freaks, some Golden Saber in 185gr. 45 ACP are +P rated. However, they are (Order # GS45APC).
http://www.remington.com/products/ammunition/handgun/golden_saber_HPJ.asp
There is every possibility that my soon to arrive Taurus 24/7 Pro Compact 45 ACP will also use the Remington Golden Saber 185gr. BJHP (Order # GS45APA). I have also been known to carry Winchester 230gr. JHP (USA45JHP) and have not felt the least inadequate. What defense load goes in my new Taurus 24/7 Pro Compact 45, will be determined by the same factors I have used for every handgun I own, reliable functioning and it's accuracy. I feel these are the only two real criteria for any round that you put through a gun, reliability and accuracy.
I know there will be some who will quote the horror stories of the early Silvertips and their lack of effectiveness. I remember reading one story in a gun magazine many years ago. Two officers responded to a family dispute. The man the call had been made about, was armed with a 12 ga shotgun. The two officers ordered the man to put it down on the ground. When he didn't comply, they opened up on him, repeatedly hitting him with their 9mm Silvertips. They stopped shooting him after he told them, "If you'll stop shooting me, I'll put the gun down. That hurts."
There was , according to some, terrible problems with these rounds. I stopped using them myself after I had a bad experience shooing a rabid animal. I shot it several times in the head at close range. The round would knock the animal down, only for it to get right back up on its feet. It took 7 rounds to end it. Just because you have to put down a sick animal doesn't mean you have to make it suffer while you're doing it. I tossed the Silvertips. My thinking was, if it doesn't kill a fairly small animal at close range with head shots, what stopping power, or lack thereof, would it have on another man?
But like I said, this was years ago and defense ammo has made huge leaps in bullet design technology. I myself have had great success with Winchester ammo and know for fact they will stand behind their ammo 100%. I had a pistol that was misfiring. I believed it was the ammo, which was Winchester Value. I contacted them and told them my problem. They paid for the ammo (including the spent cases) to be returned to them. They sent me a report on them. It was the gun, not the ammo. They sure didn't have to, but they sent me a coupon for more ammo. Have you ever seen a coupon from an ammo manufacturer for ammo?
What good is a round if your gun doesn't like it? I have seen premium ammo that certain pistols have had problems feeding. It doesn't happen all that often these days, but it can happen. If your pistol jams when you need it the most, you are in big trouble. The second thing I look for is accuracy, and I base this on two points. It must go to the point of aim, and it must shoot in a fairly tight group.
I don't care how lethal a round is reported to be. If it doesn't shoot accurately from your gun, it's of little value to you. I would much rather hit where I'm aiming with a so-called lesser round, than miss with the baddest bullet made. I also want to be able to put another in the same neighborhood it need be.
I use to have a friend years ago who had a severe case of magnumitus. He felt that his reloads had to zip out of the muzzle at near warp speed. His revolvers got a bit, shall we say, loose. These loads battered his guns to the point that he didn't keep them too long, because they wore out long before their time. He complained because he couldn't get top dollar for them when he tried to trade them off, and then later would criticize the gun for its poor workmanship..