+p

Much of the factory +P ammo today is no "hotter" than the standard ammo produces back when the lawyers weren't involved in ammo loading. (especially in .38 Special)

I still see some modern data that gets tagged as +p, but I've also noticed some data that isn't +p rated, that is producing +p velocities? Hogdon doesn't have any 9mm +p published that I've ever seen, yet there is +p 38 spcl. on their site.
GS

http://www.handloads.com/misc/saami.htm

38 Special SAAMI rating for +P is 20,000 cup.

"cup" is not velocity. The same pressure will push different bullets at different speeds. Think of pushing a marble or a bowling ball with the exact same +P "pressure" applied.

1SOW said:

http://www.handloads.com/misc/saami.htm

38 Special SAAMI rating for +P is 20,000 cup.

"cup" is not velocity. The same pressure will push different bullets at different speeds. Think of pushing a marble or a bowling ball with the exact same +P "pressure" applied.

Click to expand...

Actually, that chart lists 20,000 PSI as the limit, not 20,000 CUP. They are not the same as we all know.

I know of no factory .38 Special +P ammo that comes close to that pressure unless you shoot the "designer" ammo out there which is very expensive. (Buffalo Bore) I think there is one mainstream exception, Speer GDHP SD ammo.

Just check the load data available online and you will see the pressures are not high. Much of the load data is barely over standard pressures and I hardly see anything over 18,000 PSI.

All that makes a .38 spl +P round is that it exceeds SAAMI standard pressure limit and does not exceed the maximum SAAMI +P limit. Anywhere in between 17,001 PSI to 18,500 PSI is +P and there's absolutely no reason to believe the ammunition manufacturer or loading manual loads to the upper limit.

The older reloading manuals used to list hotter loads along with the standard loads and put a note in the pages before the data to use the lower charge level as maximum for lighter framed handguns and the a load up to the maximum listed for heavy framed handguns. Ignorant and litigious fools soon changed that. Before +P levels where agreed upon by the members of SAAMI hotter ammo was sold as "police loads" or "high velocity".

Most load data lists +P data for .38 spl and some list it for the .45 acp but none that I know list +P data for the 9mm. In the 9mm you can achieve velocities comparable to +P factory loads by proper powder selection without exceeding standard pressure. Pressure alone does not drive velocity, its pressure over time. The longer the pressure can be applied the higher the velocity which is why a slower powder often produces higher velocities.