Whats "+P"?

This is a discussion on Whats "+P"? within the Reloading forums, part of the Defensive Ammunition & Ballistics category; None of my reloading manuals list "+P" loads. Do the factory guys have some magic way to make bullets go faster without blowing up the ...

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Thread: Whats "+P"?

  1. #1
    New Member Array briankk's Avatar
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    Whats "+P"?

    None of my reloading manuals list "+P" loads. Do the factory guys have some magic way to make bullets go faster without blowing up the gun?

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  3. #2
    VIP Member Array ccw9mm's Avatar
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    +P = over-pressure, essentially.

    Magic way to avoid kaboom? None that I know of, other than experience at documenting the attempts.

    What is a given load except something that's tried, true and documented?

    If you look in any reloading manual, there will be numerous loads for a given weight of bullet. Each concoction will result in a given amount of pressure in order to yield the mix of velocity/power/flash desired. One or more of those loads might be have pressure that's higher than normal, but that has been shown to be well within the spec and capacity of the gun to handle. Factories that produce such loads often label them "+P" (or, over-pressure) loads.

    Of course, it requires a gun able to handle it. Not all can. Most mfrs seem to clearly indicate whether a given gun cannot handle +P ammo, either stamped on the gun (via lack of a +P mark) or via the manual.

    Over-pressure situations are risky, of course. If not well-managed, that pressure can blow up the gun in your hand. Caution is due, if concocting new blends yourself.
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  4. #3
    Senior Member Array ASSA9's Avatar
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    the only way you can put in more power/energy is to
    use a lighter bullet
    the lighter bullet is pushed out of the barrel easier and this
    lowers the pressure allowing you to use more powder
    more powder is the only way to rise energy numbers
    this is why you see lighter bullets in +P ammo
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    Ex Member Array Ram Rod's Avatar
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    +P= POWER!
    Quality cases (NP³), specifically engineered bullets, select powders, and added expense! If your pistol (gun) isn't designed for +P (pay more), don't use it. Check your owners manual or contact the manufacturer.

  6. #5
    Member Array Ghuqu2's Avatar
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    Both my Lee 2nd ed and my Lyman #47 show +p loadings for .38. What caliber are you looking for +p?
    BTW you forgot +p+, which is more powder/ pressure then just +p
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    Member Array laeckcrov's Avatar
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    Whenever you are trying out a new load (esp. if it's "+P") make sure you use less powder than what they tell you. Load some like that, take it out and test it, chrono it, etc. then go back and up the amount of powder.

    Repeat as necessary until the desired effects are achieved.
    The muzzle end of a .45 pretty much says, "Go Away" in every language.

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  8. #7
    New Member Array briankk's Avatar
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    Quote Originally Posted by ccw9mm View Post
    +P = over-pressure, essentially.

    Magic way to avoid kaboom? None that I know of, other than experience at documenting the attempts.

    What is a given load except something that's tried, true and documented?

    If you look in any reloading manual, there will be numerous loads for a given weight of bullet. Each concoction will result in a given amount of pressure in order to yield the mix of velocity/power/flash desired. One or more of those loads might be have pressure that's higher than normal, but that has been shown to be well within the spec and capacity of the gun to handle. Factories that produce such loads often label them "+P" (or, over-pressure) loads.

    Of course, it requires a gun able to handle it. Not all can. Most mfrs seem to clearly indicate whether a given gun cannot handle +P ammo, either stamped on the gun (via lack of a +P mark) or via the manual.

    Over-pressure situations are risky, of course. If not well-managed, that pressure can blow up the gun in your hand. Caution is due, if concocting new blends yourself.
    Pretty much as I figured. I load mainly for simi-autos, I think that "+P" is for revolvers that are a bit harder to beat up with high pressure loads..

  9. #8
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    Actually most of your major semi calibers have +P loads available. 9mm, 40 and 45 cal.
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  10. #9
    Member Array laeckcrov's Avatar
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    Quote Originally Posted by archer51 View Post
    Actually most of your major semi calibers have +P loads available. 9mm, 40 and 45 cal.
    i use 230gr +P HST in .45 as my carry ammo. Just make sure you have a well made firearm and test out your loads, you'll be fine.
    The muzzle end of a .45 pretty much says, "Go Away" in every language.

    Fast is fine, accuracy is final. Learn to be slow in a hurry.

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    VIP Member Array farronwolf's Avatar
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    Quote Originally Posted by briankk View Post
    None of my reloading manuals list "+P" loads. Do the factory guys have some magic way to make bullets go faster without blowing up the gun?
    Yea, they don't have to buy the guns out of their own pockets if they do go boom.

    Do you have a chronograph? If not your not going to be able to determine if your doing any good when developing a load. You can check for over pressure in the cases, primer pocket etc, but if you don't know how fast the bullet is leaving the barrel all your doing is guessing.

    The manufacturers use pretty expensive equipment that test pressures when making loads. I am assuming they don't market anything that exceeds SAMI standards without putting the +p or +p+ mark on the box, to cover their arses.

    Lighter bullets may go faster, but that doesn't make them necessarily better, or give them more energy all the time. When developing a load your gun, the powder and lead you use are all going to make differences, there is no easy or quick answer.
    Just remember that shot placement is much more important with what you carry than how big a bang you get with each trigger pull.
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    VIP Member Array mlr1m's Avatar
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    Just kinda thinking here. In the mid to late 60's and early 70's the two handguns i used most were loaded at higher velocities than you find today. Now those same velocities are only found in the P+ loads for those calibers.
    Back then the 357's were heavier framed. Alot of them were built on a 44 frame. I recall when the first lightweight magnum revolvers came out and the rush of police officers switching to them.

    Not long after that the word got around not to use magnum loads if you were doing alot of target shooting as they would shoot loose. We didn't have a big selection of ammo then.
    If you had a 357 you either shot full power 158 gr loads, or possibly super-vels that were sold to police.
    If you shot a 44 mag you pretty much had to use the 240 gr half jacket.
    For light loads you used the spcl's.
    The 357's and 44 mags didn't just seem to kick more back then, they actually did!

    I'm rambling here but hope that I'm making sense.
    They have lowered the velocities of these rounds because of lighter weight guns and possibly lawyers.
    They created the P+ loads to use in the guns the old cartridges were designed for.

    Michael
    Last edited by mlr1m; November 29th, 2008 at 07:03 PM. Reason: more stuff

  13. #12
    Member Array Darth AkSarBen's Avatar
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    Some information from my Taurus handbook. "For years we have said that our firearms were '+P' rated - and they were and are for SAAMI Recognized " +P " ammunition. ..... These are the only +P loads recognized by SAAMI:

    9mm Luger Standard = 35,000 +P Pressure = 38,500
    .38 Special Standard = 17,000 +P Pressure = 18,500
    .38 Super (all +P) = 36,500
    .45 Auto Standard = 21,000 +P Pressure = 23,000
    ***************
    This was out of Taurus 51 page product brochure, and the stats were from page 51.

    It is a matter of physics. Pressure develops velocity. And there are a lot of ammunition manufacturers that are going to the extreme to get their velocity up in competition. It is taxing on the gun, and generally does little for an extra edge for Self Defense, nor does it improve accuracy. Often to the contrary, extra pressure/velocity may cause the bullet to not spin right according to the rifling, and the resulting accuracy can diminish.

    When it comes to hand loads, and they manuals state the starting and maximum, these are general guidelines and starting at the low end and building up is always the best way to achieve what you are after. Without a few instruments, such as a means of velocity, such as a chronograph, the only other visible means to the reloader/shooter is how are they grouping on the paper? Lower loads/pressure that shoot good is really a goal for the target and practice area. Excessive pressure tell tales signs such as primer pockets and primers flattened, cases, etc, should be a BIG signal to back off as you are really not going to achieve better results going any higher and you might certainly shorten the life of your firearms.

    I have know Law Enforcement and other folks back in Nebraska that have shot so much .357 magnum through a S&W K frame that they literally stretched it to death and it became worn out before it's time. It was meant to handle the .357 round as a duty idea, but a steady diet really was it's demise.
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  14. #13
    VIP Member Array mlr1m's Avatar
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    "I have know Law Enforcement and other folks back in Nebraska that have shot so much .357 magnum through a S&W K frame that they literally stretched it to death and it became worn out before it's time. It was meant to handle the .357 round as a duty idea, but a steady diet really was it's demise.
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    Thats it exactly. The K frame is a lighter weight handgun. The old N frame 357's were better suited to the round but not as comfortable to carry.
    Its like the difference between a colt peacemaker and a ruger single action revolvers. Both are nice but one is better for a sustained diet of high pressure loads.

    Michael

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    I've always thought of +P as a bit of a tempest in a teapot. I tote them in my .38 but feel they're a bit overrated.

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