I think that they are called + P, what are these?

+p loads are loaded to a higher pressure than SAAMI specs. This usually results in higher vel. You should only use +p loads in fiirearms that are rated for them.

Yeah, well . . .

+P loads are loaded UP TO maximum SAAMI Spec. They DO NOT excede SAAMI Spec.

You shoot them in guns in good condition. I'd stay away from shooting them in "lightweight" frames, alloy, etc. The light frame will handle the load safely, but the frame will eventually shoot loose with a steady diet of +P.

These loads are typically used in a defense gun for defense . . . Not for target shooting or plinking.

I'll give it a shot...

Accepted SAAMI Specs for +P are a new higher pressure spec for newer guns. As an example the 38 special +P is loaded above the spec for a standard 38 special and could cause problems in an older 38 special. They are safe enough that they will likely only wreck the weaker guns but not hurt the shooter. Most new 38's are +P rated and made to work with ammo within the +P spec. It should say in the manual. Also many old guns were built plenty strong and can handle +P loads just fine. Research should be done first.

Not all calibers have +P ratings. Example: there is no industry accepted 45 (Long) Colt +P. I know at least one rifle, the 257 Roberts, has a +P rating availible.

The brass is sometimes if not always different. Obviously it has the +P headstamp but is also thicker / stronger.

Many shooters in casual conversation will call any stiff load "+P" leading to confusion. Some ammo is also loaded above even the new higher +P rating. Often this ammo is refered to as "+P+". I don't think there is any accepted +P+ specs and I have never seen a firearm manual state +P+ loads are acceptable.

In short: +P loads DO EXCEED the "normal" SAAMI spec. The higher +P spec is an industy standard on select calibers so a gun rated for them can use them (and of course standard ammo) without issue. +P+ ammo is not widely accepted and should be well researched prior to use.

Hope this helps