Thread: +P and +P+

Originally Posted by fivehourfrenzy

The P99 manual doesn't address what kind of cartridges to use. I have read that in the .40, you should use 150+gr. for the first 500 rounds. I haven't broken the 500 mark yet, but I probably will this week, and I'll be using 165gr. and/or 180gr. FMJs. I am considering getting +P or +P+ rounds if they're available in the .40, and if the gun can utilize the added pressure without being damaged. I know a little bit about bullets, but not a lot.

If you want +P or +P+ in a .40 get a 10 MM.
Standard .40 is all you want or need unless you would like a handgrenade.

If you hunt elephants start out with an elephant gun.

I would think breakin could include any factory load. If they don't proof test to greater than that get another gun.

I would stick with standard and +p loads. Those are both tested standards. +P+ means that the pressure loaded to exceeds test standards, which is a little sketchy and probably not a good thing.

The standard .40 round is stout enough as it is. I don't think I would mess around with +P+ stuff at all. Good choice of gun, by the way. I've had my P99 .40 for a year and a half now.

Well sh*t, if I can't use a +p+ round, where am I gonna get some hand grenades??? Lol. The question was more for speculation. I like to find out the limits of whatever I have before I actually get into, usually so I don't overdo it. I'm the same with cars, audio equipment, snowboards, golf clubs, guitars, and whey protein.

Can anyone explain the grain theory? I know that it's used to weigh bullets, but what advantage does using a heavier bullet than a lighter bullet give, and vice versa?

My handgrenade comment may not have been real clear. To my knowledge no company is marketing +P much less +P+ loads for the .40 because standard loads are at the max pressure limit already. Any more and the Pistol they are loaded into is the handgrenade. I realy don't think you want that.

7000 grains = 1 pound.
Heavy bullet = low velocity at given pressure
Light bullet = higher velocity at same pressure


The .40S&W is a relatively new cartridge design that began life using modern powders etc.

9MM and .45 cartridges were designed 100 years back using much less effective powder than currently available. "Newer guns only" with barrels and hardware designed to operate at higher pressures than were 1911's or lugers built in 1911 are capable of utilizing +P and in some cases, not all, +P+ ammo. If your operators manual doesn't say it is capable of utilizing +P or greater then don't use + anything. That is unless you are ambidextrious and want to lose weight.

Have fun but stay safe or don't shoot next to me.

Okay that makes sense, since I haven't seen any +p options in the .40. As far as the weight goes, it seems to me you would want a lighter, faster bullet for more penetration, and a heavier, slower bullet for less penetration. I'm trying to see whether a 180gr. would be better for self-defense, or a 165gr. would be better, or if it even matters. This is great, I'm learning all kinds of new stuff.

edit: Did some reading on bullet weights and I found a lot of contrasting views on bullet weights with respect to penetration and expansion. Also found a few things on the difference barrel lengths made.

edit: Found this: http://www.thegunzone.com/quantico-wounding.html ...I'm about halfway through it. It seems to make good sense.

Found this part particularly interesting:

"The critical wounding components for handgun ammunition, in order of importance, are penetration and permanent cavity.33 The bullet must penetrate sufficiently to pass through vital organs and be able to do so from less than optimal angles. For example, a shot from the side through an arm must penetrate at least 10-12 inches to pass through the heart. A bullet fired from the front through the abdomen must penetrate about 7 inches in a slender adult just to reach the major blood vessels in the back of the abdominal cavity. Penetration must be sufficiently deep to reach and pass through vital organs, and the permanent cavity must be large enough to maximize tissue destruction and consequent hemorrhaging.

Several design approaches have been made in handgun ammunition which are intended to increase the wounding effectiveness of the bullet. Most notable of these is the use of a hollow point bullet designed to expand on impact.

Expansion accomplishes several things. On the positive side, it increases the frontal area of the bullet and thereby increases the amount of tissue disintegrated in the bullet's path. On the negative side, expansion limits penetration. It can prevent the bullet from penetrating to vital organs, especially if the projectile is of relatively light mass and the penetration must be through several inches of fat, muscle, or clothing.34

Increased bullet mass will increase penetration. Increased velocity will increase penetration but only until the bullet begins to deform, at which point increased velocity decreases penetration. Permanent cavity can be increased by the use of expanding bullets, and/or larger diameter bullets, which have adequate penetration. However, in no case should selection of a bullet be made where bullet expansion is necessary to achieve desired performance.35 Handgun bullets expand in the human target only 60-70% of the time at best. Damage to the hollow point by hitting bone, glass, or other intervening obstacles can prevent expansion. Clothing fibers can wrap the nose of the bullet in a cocoon like manner and prevent expansion. Insufficient impact velocity caused by short barrels and/or longer range will prevent expansion, as will simple manufacturing variations. Expansion must never be the basis for bullet selection, but considered a bonus when, and if, it occurs. Bullet selection should be determined based on penetration first, and the unexpanded diameter of the bullet second, as that is all the shooter can reliably expect.

It is essential to bear in mind that the single most critical factor remains penetration. While penetration up to 18 inches is preferable, a handgun bullet MUST reliably penetrate 12 inches of soft body tissue at a minimum, regardless of whether it expands or not. If the bullet does not reliably penetrate to these depths, it is not an effective bullet for law enforcement use.36

Given adequate penetration, a larger diameter bullet will have an edge in wounding effectiveness. It will damage a blood vessel the smaller projectile barely misses. The larger permanent cavity may lead to faster blood loss. Although such an edge clearly exists, its significance cannot be quantified.

An issue that must be addressed is the fear of over penetration widely expressed on the part of law enforcement. The concern that a bullet would pass through the body of a subject and injure an innocent bystander is clearly exaggerated. Any review of law enforcement shootings will reveal that the great majority of shots fired by officers do not hit any subjects at all. It should be obvious that the relatively few shots that do hit a subject are not somehow more dangerous to bystanders than the shots that miss the subject entirely.

Also, a bullet that completely penetrates a subject will give up a great deal of energy doing so. The skin on the exit side of the body is tough and flexible. Experiments have shown that it has the same resistance to bullet passage as approximately four inches of muscle tissue.37

Choosing a bullet because of relatively shallow penetration will seriously compromise weapon effectiveness, and needlessly endanger the lives of the law enforcement officers using it. No law enforcement officer has lost his life because a bullet over penetrated his adversary, and virtually none have ever been sued for hitting an innocent bystander through an adversary. On the other hand, tragically large numbers of officers have been killed because their bullets did not penetrate deeply enough."

This is also a great website for reading... http://www.angelfire.com/art/enchanter/terminal.html

Definitely puts physics to [our] every day use.

Here's a little quote from a friend of mind that tell's it the best.
"Shot placement is King.
Penetration is Queen.
Everything else is Angels dancing on the head of a pin". Thanks Mr Erich.
Use a good brand ammo for your gun and don't worry about all that manufacturing hype about +p-+p+.

There's no SAAMI spec for +P or +P+ in .40S&W. Anyone claiming one is outside of industry parameters, and therefore highly suspect.

Basically what I got from all the reading is this:

I. Three factors on ability to incapacitate are penetration, bullet diameter, and expansion.
1. Penetration is key factor because a bullet must penetrate deep enough to cause damage to the CNS or vital organs, yet should not overpenetrate and exit the BG. **note that in order for a bullet to exit the skin of a human from the inside, it must have enough terminal energy and momentum to penetrate 4" of muscle tissue.
2. Bullet diameter is second priority because of permanent/temporary cavities.
3. Expansion is last because only 60-70% of bullets that are designed to expand actually do.

II. Terminal velocity, energy, and momentum are affected by bullet diameter, weight, and sectional density.
1. Bullets within a constant diameter - terminal V, E, and M are dictated by weight and SD, which are relative to each other when bullet diameter is constant.
2. Sectional density is a measure of the ratio for diameter to weight, meaning all three are related.
3. Diameter, weight, and SD can be used to calculate terminal V, E, and M for any bullet diameter and weight for any distance.

General rule of thumb: in the chosen bullet diameter, use the highest weight available (which is 180gr. for a .40S&W), then choose the highest tolerable muzzle velocity, or muzzle energy. MV and ME are positively related...higher velocity equals higher energy. The higher the MV or ME in the chosen diameter, the harder the recoil (due to momentum). My self-defense rounds are CCI Gold Dot 180gr. HPs, so since they weigh 180 grains and have a muzzle velocity of 1,025fps (and muzzle energy of 420 lbs/ft), the momentum generated when MV and ME are reached is 26.357 lbs/ft.

Not really all that important, but it's interesting stuff.

To take it a step further I haven't heard of any +P+ loads for any cartridge that is within SAAMI specs? I thought SAAMI developed +P loads for old cartridges like the 38 SPL or 45 ACP that with improvements in steel, etc will withstand greater pressure and hence for use in a modern firearm that is +P rated by the manufacturer. The +P+ label has to produced by those that wish to operate beyond SAAMI pressure specs and as such a firearm manufacturer won't certify a particular firearm to operate beyond his own specs.

I reload and usually get best accuracy working below maximun and certainly the most enjoyment there as well. Why blow up your firearm and maybe yourself as well?

Originally Posted by TerryP

Why blow up your firearm and maybe yourself as well?

It's just speculation versus experimentation. Just like I'd rather take someone's word on the maximum speed of my car out of the factory instead of topping it out on the road, I'd rather find out how far I can push a gun instead of actually finding out myself.


Well, actually on the first one I'd rather find out myself. Why believe that a car tops out at 152mph instead of hitting 152mph on the interstate instead? Don't answer that.