I was wondering where I could find information on the meaning of +P and +P+ when referring to handgun ammo.  I understand from context that it is a 'hotter' load, but what exactly does it mean?  I tried searching but search engines count the '+' as a search qualifier and it never works.

Thanks for your help

I have no idea what the "P" stands for.   I would assume is stands for "powder" or "POW!".   +P and +P+ are often used by different manufacturer's to label a round that is loaded to higher pressure than their normal offering in that caliber/weight.

+P is regulated by industry standards, meaning there is a max amount of pressure for a +P in a certain caliber and manufacturers shouldn't exceed it.   +P+ isn't recognized by industry standard and is a label certain manufacturers use.  Also, some loads boxed as regular loads are hotter than some +P loads from other folks, and sometimes within the same brand.   There is no rhyme or reason.

In general, +P means is supposed to mean hotter than regular.  +P+ is supposed to mean it's hotter than +P.

This is all based off memory.  So I could be wrong.

Don't try shooting +P or +P+ unless your handgun has a full supported chamber and is supposed to shoot these hotter loads or you're gonna be in trouble.

Well I sold my Taurus PT100 in .40 and bought a Sig P229 in 357 Sig.  None of the ammo I have bought or even seen has the +P or +P+ on it.  I have noticed differances in ammo that I have bought though.  The stuff I bought at the gunshow was reloads from a company that the shooting range guy knows well and actually resells their ammo for them.  I have also shot some Gold Dots that are definitely loaded hotter, but there is no +P or +P+ marking on the box.

I have always assumed the P stands for pressure, as +P and +P+ loads are loaded to higher pressure than stnadard loads.

Quoted: I have always assumed the P stands for pressure, as +P and +P+ loads are loaded to higher pressure than stnadard loads.

Correct

Quoted: Well I sold my Taurus PT100 in .40 and bought a Sig P229 in 357 Sig.  None of the ammo I have bought or even seen has the +P or +P+ on it.  I have noticed differances in ammo that I have bought though.  The stuff I bought at the gunshow was reloads from a company that the shooting range guy knows well and actually resells their ammo for them.  I have also shot some Gold Dots that are definitely loaded hotter, but there is no +P or +P+ marking on the box.

that is because there are only iirc 4 saami recognized +p loads: 9mm+p, .38spl +p, .45acp +p, and .257roberts +p.  often you will see .38super listed as +p but that is just to note that it was much more powerful than older .38 chamberings.  basically there is a pressure limit for standard loads and another for +p loads.  but there is technically no upper limit for +p+ and that is not saami recognized.  +p is generally ok in most military type handguns--sigs, rugers, glocks, hk, etc.  but if you are concerned i suggest checking your manual or contacting the manufacturer.