I was curious to know at what point my hand loads become classified as a +P load... I am also curious to find out how I know if my pistol is capable of handling +P loads. After shopping around for defense loads, it seems that quite a few of the 9mm rounds out there are designated as +P.
When does it become +P?
- Thread starter TrickyD
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rcmodel
Member in memoriam
There is no way for a handloader to know what pressure his load actually runs in his gun.
You can look up load data for +P in .38 Spl in your load manual, and load to that level safely.
+P 9mm & .45 ACP data is not generally published.
There is no +P standard for most other calibers.
But if brand XYZ says it's +P gets 1,250 FPS, and the Hodgdon or Hornady, or Speer, or Lyman reloading manual says you can get 1,350 with less then +P pressure?
You got better then +P performance with standard pressure.
Bottom line is, don't worry about +/- 100 FPS velocity.
What you shoot with it will never ever know the difference, if you hit it.
And in general, it is way easier to hit it more then once, fast with standard pressure loads then with +P loads.
rc
You can look up load data for +P in .38 Spl in your load manual, and load to that level safely.
+P 9mm & .45 ACP data is not generally published.
There is no +P standard for most other calibers.
But if brand XYZ says it's +P gets 1,250 FPS, and the Hodgdon or Hornady, or Speer, or Lyman reloading manual says you can get 1,350 with less then +P pressure?
You got better then +P performance with standard pressure.
Bottom line is, don't worry about +/- 100 FPS velocity.
What you shoot with it will never ever know the difference, if you hit it.
And in general, it is way easier to hit it more then once, fast with standard pressure loads then with +P loads.
rc
1SOW
Member
Your owners manual should contain recommendations and any ammo restrictions. If you don't have one, they are often available online.
rcmodel +1
evan price
Member
A BIG PLUS ONE to RCModel's post.
+P means that the pressure of the loaded round exceeds the SAAMI acceptable pressure limit for the basic caliber. It is an overpressure round. For example, in 38 Special, SAAMI's current pressure spec is not to exceed 17,000 PSI for basic 38 Special.
Some cartridges (Such as 38 Special, 9mm Luger, 45 ACP) SAAMI has tested and determined a safe overpressure loading for use in guns which have been proven to be safe handling the higher pressure. These loads also have a maximum pressure limit. 38 Special +P loads cannot currently exceed 18,500 psi.
Once you exceed the +P pressure limit, you are now officially in "+P+" territory. The only specifications for +P+ loads is that they exceed published industry standards for +P. It could be 5% higher, it could be 50% higher.
The only way to safely develop overpressure loads is to use a pressure transducer and a test barrel- resources of a ballistics laboratory.
Most modern duty handguns will accept +P loadings however it is always best to consult your owner's manual or the manufacturer to be sure.
+P means that the pressure of the loaded round exceeds the SAAMI acceptable pressure limit for the basic caliber. It is an overpressure round. For example, in 38 Special, SAAMI's current pressure spec is not to exceed 17,000 PSI for basic 38 Special.
Some cartridges (Such as 38 Special, 9mm Luger, 45 ACP) SAAMI has tested and determined a safe overpressure loading for use in guns which have been proven to be safe handling the higher pressure. These loads also have a maximum pressure limit. 38 Special +P loads cannot currently exceed 18,500 psi.
Once you exceed the +P pressure limit, you are now officially in "+P+" territory. The only specifications for +P+ loads is that they exceed published industry standards for +P. It could be 5% higher, it could be 50% higher.
The only way to safely develop overpressure loads is to use a pressure transducer and a test barrel- resources of a ballistics laboratory.
Most modern duty handguns will accept +P loadings however it is always best to consult your owner's manual or the manufacturer to be sure.
The closest you're going to get as a reloader to knowing your pressures is using what's in your load manual. You need to load as close to the listed OAL as you can, use the same bullet that the data calls for, and use the minimum powder charge for the given range.
Take this ammo to the range and shoot it over a chrono. Look at the velocity. If by some miracle, your velocities are similar to what's in the book, it would be logical to say that your ammo is at the lowest pressure listed for that powder/bullet combo. Most load manuals have pressure ranges; they list min and max.
The problem with picking a powder charge in the middle (if you're trying to determine pressure AND assuming your velocities for a minimum charge mirrored what's in the manual) is that you don't know the pressure curve of the powder as it progresses from a minimum charge to a maximum charge. How does it arrive from the minimum to the maximum? Unless you have a graphical representation of the pressure curve for that loading, you will not know what values to expect within the range of min to max.
Ok, so that was a lot of typing. In short, you probably will not know what pressure you are at. You could maybe get a ballpark number, but nothing concise. The reason that actual velocities you get at the range seem lower than the book is because they are probably using a test barrel, a length of which we do not know. If you're not matching velocities with a 4.5" to 5" barrel, it's safe to say they are probably using something that is 7-8 inches long, so using your chrono'd velocities is a crapshoot at best. There are just too many unknowns.
Take this ammo to the range and shoot it over a chrono. Look at the velocity. If by some miracle, your velocities are similar to what's in the book, it would be logical to say that your ammo is at the lowest pressure listed for that powder/bullet combo. Most load manuals have pressure ranges; they list min and max.
The problem with picking a powder charge in the middle (if you're trying to determine pressure AND assuming your velocities for a minimum charge mirrored what's in the manual) is that you don't know the pressure curve of the powder as it progresses from a minimum charge to a maximum charge. How does it arrive from the minimum to the maximum? Unless you have a graphical representation of the pressure curve for that loading, you will not know what values to expect within the range of min to max.
Ok, so that was a lot of typing. In short, you probably will not know what pressure you are at. You could maybe get a ballpark number, but nothing concise. The reason that actual velocities you get at the range seem lower than the book is because they are probably using a test barrel, a length of which we do not know. If you're not matching velocities with a 4.5" to 5" barrel, it's safe to say they are probably using something that is 7-8 inches long, so using your chrono'd velocities is a crapshoot at best. There are just too many unknowns.
This is a good reason to follow a reliable load data source. Don't go over maximum, and don't go below minimum. Choose a manual with data that you like, and use it.
If you choose to go above max, be aware of the risks. I do not recommend overcharged reloads.
If you choose to go above max, be aware of the risks. I do not recommend overcharged reloads.
fiftybmg
member
Your reloading manual will indicate the maximum load. If you go over that, it's +P.
The safety problem is there is no guideline to indicate the maximum for +P, and when +P becomes +P+, or even what the safe limit is in the pursuit of plusses.
My view on all this is simple - if you want either heavier bullets than the load spec, or higher velocity than the load spec for your caliber, get a bigger caliber.
The safety problem is there is no guideline to indicate the maximum for +P, and when +P becomes +P+, or even what the safe limit is in the pursuit of plusses.
My view on all this is simple - if you want either heavier bullets than the load spec, or higher velocity than the load spec for your caliber, get a bigger caliber.
4895
Member
I would assume that +P is reached as soon as you go beyond the max published standard load listed for your particular combination.
For example, a friend of mine loads for his 7mm mag. He uses H870 powder with a 175 grain bullet. He also uses a 30 year old load book and loads about 3.5 grains over the max for that load. He says he can see the bullet through the scope hit the target before he feels the recoil. That is definately +P+. His primer pockets are loose after 1 load with new brass with that load as well. Like he says, when the brass hits the ground, don't bother picking it up.
For example, a friend of mine loads for his 7mm mag. He uses H870 powder with a 175 grain bullet. He also uses a 30 year old load book and loads about 3.5 grains over the max for that load. He says he can see the bullet through the scope hit the target before he feels the recoil. That is definately +P+. His primer pockets are loose after 1 load with new brass with that load as well. Like he says, when the brass hits the ground, don't bother picking it up.
There is a reason for published maximums - actually several reasons - not the least of which is you only get one set of eyes, ears and fingers.
I'm not the boss of anyone but me, but in every passtime there are always those who do their very best to prove Mr Darwin and Mrs Gump were prophets. I put loading over published max in that same category of needless risk. Was it John Wayne who said "Life is hard, it's even harder when you're stupid."?
I'm not the boss of anyone but me, but in every passtime there are always those who do their very best to prove Mr Darwin and Mrs Gump were prophets. I put loading over published max in that same category of needless risk. Was it John Wayne who said "Life is hard, it's even harder when you're stupid."?
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