Jim March
Member
Snagglepuss: there is an organization called "SAAMI" (Sporting Arms and Ammunition Manufactrer's Institute) that sets standards for each caliber in terms of maximum pressure levels as measured in "PSI" (pounds/square inch). The higher the pressure, the more "oomph" more or less, and the more stress on the gun.
"+P" means it's loaded up to 10% over SAAMI specs for the caliber. USUALLY. There's an extreme exception in the 45LC caliber - when you see that in "+P" it's loaded WAY more than 10% over and will usually be marked "Ruger ONLY!!!". There's a long story there we need not get into.
"+P+" means one of two things: it's ammo meant for sub-machine guns that are way bigger and tougher than pistols of the same caliber, or it's part of an old pattern of US law enforcement fraud and is marked "law enforcement sales only" or similar.
Let me explain that latter. Any gun that can shoot the 357Magnum caliber (first shipped in 1937) can also shoot the old 38Special ammo (dating to 1895). This is because of the original design of the 357 - they took the 38Spl shell and stretched it just enough that the 357 ammo wouldn't fit in the older 38Spl guns - to avoid blowing the older guns up.
Flash forward to the early 70s. By then the 357 was the most popular police handgun and ammo. But then the "Dirty Harry" movies came out and made the word "MAAGNUM!!!" an "evil thing" that "only a psycho" would shoot.
So rather than put 357 MAAAAGNUMS in their guns, they special ordered super-hot 38Spl "+P+" stuff that was safe to fire only in the 357 guns. That way, on the witness stand, street cops could say "oh no, we didn't blow him away with MAGNUMS, we used nice mild 38s!"
No, I'm not kidding.
Unless you REALLY know what you're doing, avoid "+P+" anything - the concept migrated to the 9mm and possibly other calibers in police circles.
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Gunpowder type: various powders burn at different speeds and have different amounts of "ooomph" for the same volume of powder. The trick in loading up any given round is to match the burn rate of the powder to the length of the barrel - perfection is when the powder stops burning right as the bullet clears the end of the barrel. You don't have any waste as the air is filled with burning powder, you also don't have the bullet slowing down in the last part of the barrel from friction because there's no more burn behind it.
Since heavier bullets get moving slower (due to momentum), you generally use a slower-burn powder...otherwise the pressure spike will be severe as the powder tries to rapidly push something that doesn't want to start moving.
Two other factors: "bulkier" powder will be more expensive to deal with - powders are generally similar in cost for the volume, but if a given powder needs twice as much in each shell, costs go up. BUT you don't want a situation where there's only a tiny amount of powder in each shell - the flash from the primer at the rear might travel across the top of the "powder pool" and set it all off at once rather than starting a burn from the back. Some handloaders (people brewing their own ammo) will put powder in the bottom of the shell, fill the rest with cornstarch or something to pack it towards the rear and then load the bullet.
For more than that on loading, go get a reloading/handloading manual
.
"+P" means it's loaded up to 10% over SAAMI specs for the caliber. USUALLY. There's an extreme exception in the 45LC caliber - when you see that in "+P" it's loaded WAY more than 10% over and will usually be marked "Ruger ONLY!!!". There's a long story there we need not get into.
"+P+" means one of two things: it's ammo meant for sub-machine guns that are way bigger and tougher than pistols of the same caliber, or it's part of an old pattern of US law enforcement fraud and is marked "law enforcement sales only" or similar.
Let me explain that latter. Any gun that can shoot the 357Magnum caliber (first shipped in 1937) can also shoot the old 38Special ammo (dating to 1895). This is because of the original design of the 357 - they took the 38Spl shell and stretched it just enough that the 357 ammo wouldn't fit in the older 38Spl guns - to avoid blowing the older guns up.
Flash forward to the early 70s. By then the 357 was the most popular police handgun and ammo. But then the "Dirty Harry" movies came out and made the word "MAAGNUM!!!" an "evil thing" that "only a psycho" would shoot.
So rather than put 357 MAAAAGNUMS in their guns, they special ordered super-hot 38Spl "+P+" stuff that was safe to fire only in the 357 guns. That way, on the witness stand, street cops could say "oh no, we didn't blow him away with MAGNUMS, we used nice mild 38s!"
No, I'm not kidding.
Unless you REALLY know what you're doing, avoid "+P+" anything - the concept migrated to the 9mm and possibly other calibers in police circles.
--------
Gunpowder type: various powders burn at different speeds and have different amounts of "ooomph" for the same volume of powder. The trick in loading up any given round is to match the burn rate of the powder to the length of the barrel - perfection is when the powder stops burning right as the bullet clears the end of the barrel. You don't have any waste as the air is filled with burning powder, you also don't have the bullet slowing down in the last part of the barrel from friction because there's no more burn behind it.
Since heavier bullets get moving slower (due to momentum), you generally use a slower-burn powder...otherwise the pressure spike will be severe as the powder tries to rapidly push something that doesn't want to start moving.
Two other factors: "bulkier" powder will be more expensive to deal with - powders are generally similar in cost for the volume, but if a given powder needs twice as much in each shell, costs go up. BUT you don't want a situation where there's only a tiny amount of powder in each shell - the flash from the primer at the rear might travel across the top of the "powder pool" and set it all off at once rather than starting a burn from the back. Some handloaders (people brewing their own ammo) will put powder in the bottom of the shell, fill the rest with cornstarch or something to pack it towards the rear and then load the bullet.
For more than that on loading, go get a reloading/handloading manual
.