ruger p90

Question
what kind of ammo should i use in a Ruger p90 i would like know what brand,grain full jacket and hollow point.

Answer
You can use any standard .45 ACP ammunition in the gun. Beyond that, what you use will be dictated by your needs.  If you are simply punching paper, there is no reason not to go with standard 230 gr FMJ military ball, which is often the cheapest factory ammuntion.

If you are loading your own ammunition, you've got choices of jacketed, plated, or plain lead in ball or wad-cutter configuration in weights from 185-200-230 grain.

For self-defense, there are different schools of thought. The best would be a heavy bullet moving fast. Since that is not an option with the .45 you have to choose between light and fast, or heavy and slow, and each school of thought has their advocates.

My personal observations lead me to believe that the equation is cartridge/caliber specific, and for the .45 ACP, I prefer the heavy/slow approach, meaning that I like the 230 gr. bullets, which will mean in most cases a projectile traveling at under 900 fps.

In a self defense cartridge for the .45 I like the 230 gr. Remington Golden Saber. Expensive as the stuff is, I would run a box or two through it before I carried it. The .45 is a wide, short cartridge and often has proclivities regarding feeding. The GS is great if it works in your gun, useless if it does not.

If for some reason you can't find any HP that will feed, I would not feel disadvantaged carrying a .45 will 230 gr. ball ammunition.