What's "+P"?

Ed Dixon · September 18, 2002, 11:59 PM

I see this often in reference to .38 specials. Is it just a hotter load? Is it used regarding other calibers? How long's this designation been around? What cautions apply?

labgrade · September 19, 2002, 12:12 AM

+P means "extra pressure" over standard loading. It does not necessarily wquate to higher velocity.

I dunno when it came into vogue - probablly a marketing hype not too long after Lee Juras' SuperVels ...

I've some 9mm +Ps.

Some of the lightweight alloy firearms shouldn't be fed at all, some OK but not a steady diet. Manual should say what, if any restrictions.

444 · September 19, 2002, 12:15 AM

I won't be able to give you a technical answer but it means high for the caliber presure. This usually translates to higher velocity. Obviously +P ammo should only be fired in a gun with the strength to handle it. For example it is a general rule that K-Framed S&W revolvers can't take a steady diet of +P ammo, you need to move up to an L frame or possibly even an N frame if you intend to shoot a whole lot of +P ammo. Most guns of modern manufacture arn't going to come apart from shooting +P ammo, it is just going to accellerate the wear on the gun.

C.R.Sam · September 19, 2002, 03:24 PM

Bear in mind that +P denotes PEAK pressure up to 10 percent above SAAMI specs for that cartridge.

And +P+ (not a SAAMI term) denotes an indeterminate higher PEAK pressure.

Neither +P nor +P+ have any direct bearing on bullet energy or performance.

Easy to have a bullet and case combo that gives poor bullet performance at extremely high PEAK pressure with one powder and outstanding performance at standard PEAK pressure with a different powder.

+P and +P+ are indicators of how much stress is placed on the gun, they are NOT indicators of how hard the bullet is being pushed.

Shop your ammo by performance. Velocity, wt, expansion, accuracy, consistancy etc.

Sam

Ed Dixon · September 19, 2002, 10:20 PM

Okay, then are they ever the better performer? I'm getting the impression that if so, not often, and if that's the case what's the allure? Is this more macho than ballistic?

WESHOOT2 · September 20, 2002, 04:36 AM

"+P" and "+P+" are often attached to ammo that actually does go faster, but as C.R.Sam mentioned, not always.

Regular SAAMI pressures are based on lowest-common-denominator guns.
Some modern guns MAY be slightly stronger than those used to set SAAMI safe pressures.

More important; can you hit what you intend? Consistently? With sufficient power?

Macho is not part of the equation.............

444 · September 20, 2002, 11:05 AM

You bring up a very good point that I had never really considered before; probably because I am a handloader and thanks to manuals have a pretty good idea of what pressure and velocity I am going to get from a given load. You can look at a loading manual and find loads that give greater velocity with less pressure and simply buy that powder and go to town. But why, would someone load a higher pressure load, if it doesn't give you increased performance ? I don't know, but I can guess. I would appreciate some of our more savy members to educate the rest of us on the correct answer. My guess is that factory ammo is loaded with "cannister powder". As I understand it, these powders are purchased in huge volume as a cost cutting measure and loads might be worked up for several different calibers using the same powder. So as a handloader, I might choose a given powder for a given application. Where a factory makes a powder fit their application whether it is the best powder for the job or not. This may be all wrong and I freely admit this was just something I dreamed up.

DAVID NANCARROW · September 20, 2002, 11:26 AM

444, I think you're on to something there. Take a look at Lyman's 47th, and you will frequently see factory equivalent loads which are almost never the top loads in velocity or pressure.
It appears that ammo manufacturers will frequently select a powder which meets a decent velocity standard and wisely a pretty good safety margin.
Not really a bad place to be, and of course, they would not go to the trouble a dedicated handloader goes through because few would want to pay the price increase.
Factory ammo is much better than it used to be, but they will not compete with a dedicated handloader on a round for round accuracy basis.

444 · September 20, 2002, 11:40 AM

As far as accuracy, I personally would think that factory ammo is great. But if you want max velocity, you pretty much need to either handload, or buy ammo from a custom or semi-custom shop.

September 18, 2002, 11:59 PM	#1
Ed Dixon Senior Member Join Date: September 5, 2000 Location: Ireland Posts: 308	What's "+P"? I see this often in reference to .38 specials. Is it just a hotter load? Is it used regarding other calibers? How long's this designation been around? What cautions apply? __________________ I hate quotes. Tell me what you know. - Emerson

September 19, 2002, 12:15 AM	#3
444 Senior Member Join Date: November 20, 2000 Location: Ohio Posts: 3,968	I won't be able to give you a technical answer but it means high for the caliber presure. This usually translates to higher velocity. Obviously +P ammo should only be fired in a gun with the strength to handle it. For example it is a general rule that K-Framed S&W revolvers can't take a steady diet of +P ammo, you need to move up to an L frame or possibly even an N frame if you intend to shoot a whole lot of +P ammo. Most guns of modern manufacture arn't going to come apart from shooting +P ammo, it is just going to accellerate the wear on the gun. __________________ You know the rest. In the books you have read How the British Regulars fired and fled, How the farmers gave them ball for ball, From behind each fence and farmyard wall, Chasing the redcoats down the lane, Then crossing the fields to emerge again Under the trees at the turn of the road, And only pausing to fire and load.

September 19, 2002, 10:20 PM	#5
Ed Dixon Senior Member Join Date: September 5, 2000 Location: Ireland Posts: 308	Okay, then are they ever the better performer? I'm getting the impression that if so, not often, and if that's the case what's the allure? Is this more macho than ballistic? __________________ I hate quotes. Tell me what you know. - Emerson

September 20, 2002, 04:36 AM	#6
WESHOOT2 Senior Member Join Date: February 20, 1999 Location: home on the range; Vermont (Caspian country) Posts: 14,324	VELOCITY MATTERS "+P" and "+P+" are often attached to ammo that actually does go faster, but as C.R.Sam mentioned, not always. Regular SAAMI pressures are based on lowest-common-denominator guns. Some modern guns MAY be slightly stronger than those used to set SAAMI safe pressures. More important; can you hit what you intend? Consistently? With sufficient power? Macho is not part of the equation............. __________________ . "all my ammo is mostly retired factory ammo"

September 19, 2002, 12:12 AM	#2
labgrade Member In Memoriam Join Date: November 29, 1999 Location: west of a small town, CO Posts: 4,346	+P means "extra pressure" over standard loading. It does not necessarily wquate to higher velocity. I dunno when it came into vogue - probablly a marketing hype not too long after Lee Juras' SuperVels ... I've some 9mm +Ps. Some of the lightweight alloy firearms shouldn't be fed at all, some OK but not a steady diet. Manual should say what, if any restrictions.

September 19, 2002, 03:24 PM	#4
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	Bear in mind that +P denotes PEAK pressure up to 10 percent above SAAMI specs for that cartridge. And +P+ (not a SAAMI term) denotes an indeterminate higher PEAK pressure. Neither +P nor +P+ have any direct bearing on bullet energy or performance. Easy to have a bullet and case combo that gives poor bullet performance at extremely high PEAK pressure with one powder and outstanding performance at standard PEAK pressure with a different powder. +P and +P+ are indicators of how much stress is placed on the gun, they are NOT indicators of how hard the bullet is being pushed. Shop your ammo by performance. Velocity, wt, expansion, accuracy, consistancy etc. Sam

September 20, 2002, 11:05 AM	#7
444 Senior Member Join Date: November 20, 2000 Location: Ohio Posts: 3,968	You bring up a very good point that I had never really considered before; probably because I am a handloader and thanks to manuals have a pretty good idea of what pressure and velocity I am going to get from a given load. You can look at a loading manual and find loads that give greater velocity with less pressure and simply buy that powder and go to town. But why, would someone load a higher pressure load, if it doesn't give you increased performance ? I don't know, but I can guess. I would appreciate some of our more savy members to educate the rest of us on the correct answer. My guess is that factory ammo is loaded with "cannister powder". As I understand it, these powders are purchased in huge volume as a cost cutting measure and loads might be worked up for several different calibers using the same powder. So as a handloader, I might choose a given powder for a given application. Where a factory makes a powder fit their application whether it is the best powder for the job or not. This may be all wrong and I freely admit this was just something I dreamed up.

September 20, 2002, 11:26 AM	#8
DAVID NANCARROW Senior Member Join Date: November 5, 2000 Location: Wyoming Posts: 1,761	444, I think you're on to something there. Take a look at Lyman's 47th, and you will frequently see factory equivalent loads which are almost never the top loads in velocity or pressure. It appears that ammo manufacturers will frequently select a powder which meets a decent velocity standard and wisely a pretty good safety margin. Not really a bad place to be, and of course, they would not go to the trouble a dedicated handloader goes through because few would want to pay the price increase. Factory ammo is much better than it used to be, but they will not compete with a dedicated handloader on a round for round accuracy basis.

September 20, 2002, 11:40 AM	#9
444 Senior Member Join Date: November 20, 2000 Location: Ohio Posts: 3,968	As far as accuracy, I personally would think that factory ammo is great. But if you want max velocity, you pretty much need to either handload, or buy ammo from a custom or semi-custom shop.