+p or +p+ 9mm load data

Writing things like that won't help your cause and make folks think your doing something that's a good idea.

Agreed but let's keep some things in perspective. I'm talking about +p or maybe a little higher.

I'm just saying the AR platform would be a good choice for this type of experimentation.

(There are also blowback and DI 9mm setups)
 
I've always read that +P loading should be only done with NEW brass and not multifired cases and fired +P cases should not be reloaded again at +P levels. May not be necessary but would be a safer practice? Brass is the limiting factor and not just barrels or bolt lock-ups.
 
(There are also blowback and DI 9mm setups)

I am going to assume you have a blowback 9mm like the 999 out of 1000 rest of us.

If you were thinking of dropping $1600+ on a Sig MPX why don't you just save $1200 of that and invest the rest in a 357 or 44 mag carbine for killing your hogs, either will do a better job, with standard load data.
 
Lets see, 223 is a little tiny bullet.

A .357 is a much bigger bullet.

Chamber is designed for ? (probably 9mm pressures as there is not a case made that will do 223 pressure. )

Err what part of the country do you live in?
 
You could "invent" your own round and call it "pistol only" if you like. A rimless 357 maximum that would be much more effective than even a +P+ 9mm AR, with its much larger case volume.

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I think you should follow your own advice.

April 29, 2017, 05:34 AM #18
black_hog_down
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Join Date: May 13, 2016
Posts: 78
I hunt hogs on land that allows shotguns and pistol calibers. This is county land and what they really mean is 357 or 44 Magnum. The way my agreement is actually written I could use a pistol length AR15 but I have access to a bunch of nice land and I'm not gonna push it.

Except I would quit loading the over max 357 too and just buy a 44 mag and call it a day. If over max 357 wasn't enough for you, you are wasting time and money messing with 9x19.
 
Amazing how quickly things turn on these boards.

Again, I'm just asking about +p or maybe a bit hotter.

I also think that the AR platform is a good candidate for this kind of thing.

Everybody relax.
 
I think you should follow your own advice.



Except I would quit loading the over max 357 too and just buy a 44 mag and call it a day. If over max 357 wasn't enough for you, you are wasting time and money messing with 9x19.
Nice work Columbo. I own more than one gun. I've experimented with the 357 and 44 and now I'm tinkering with 9mm. Is that a crime?
 
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Winchester pretty much did that several years ago, the 9mm Win Mag or 9x29, meant for the Wildey but nobody was much interested in a smallbore version of that big gun.
 
Actually I was thinking making the case the same length as a 357 magnum.

Or shorting a 223 case just at the shoulder (36mm), much longer than 9x29.

But then if I want more power than the standard 9mm, I just move up to a

44 or 45.
 
Problem is, the head diameter of .223 is only .376; 9mm is .391 with taper, and even the straight .38 Super is .384". I am not sure you can get a .355" bullet in a shortened .223 with good cartridge and chamber geometry.
Jeff Cooper and some of his buds did, though; so it is possible.
 
Nice work Columbo. I own more than one gun. I've experimented with the 357 and 44 and now I'm tinkering with 9mm. Is that a crime?

No, not a crime at all.

I like the idea too but I know I don't know enough yet to think I can safely pull that off.

Just thinking out loud but two threads where your asking about loading above max load data that can be found in any manual...
 
Black-Hog-Down said:
I'm talking about +p or maybe a little higher.

Since "a little higher" is outside the SAAMI limits, it's what the commercial makers call +P+. There is no upper limit on +P+, because, by definition, it's outside SAAMI limits. It is going to be outside published loads, and hence the warning added to the original post, even if it's only by a little bit extra.

Now the dirty little secret that may cheer you up. SAAMI specs are for manufacturers insuring compatibility in all weapons of the same chambering. Most people don't understand how the SAAMI standards work and handloading manuals don't typically use the SAAMI numbers the way manufacturers do: they load lower.

Here's part of how the SAAMI statistical method is used:
The maximum pressure number we commonly see is called the Maximum Average Pressure, or MAP. This is the highest 10-shot peak pressure average a random sample of 10 freshly loaded rounds produces, fired in a minimum size chamber with the powder back over the flash hole (highest pressure for position-sensitive loads). But it is a maximum for the average and not the maximum for individual rounds that contributed to that average. Those individual rounds go both above and below the average to result in that average.

The actual highest individual cartridge pressure is determined by another number called the Maximum Extreme Variation (MEV), which limits extreme spread of peak pressure among the ten rounds in the test sample to about 18% above the MAP in the worst possible case. That case is rarely, if ever, seen, and a more reasonable expectation is the highest individual peak pressure will fall within the limit used by the European CIP, which is 15% above MAP.

Handloading data manuals don't use the MAP as an average. They use it as an absolute limit. If you look at the maximum loads in Hodgdon's data, for example, their pressure listed is below MAP and isn't the same among different powders. That's because they take the variation into account and adjust the maximum load so the highest pressure value the record for an individual cartridge never exceeds the MAP number. This approach is spelled out in Hodgdon's printed manual, where they advise you that the highest maximum load pressure you see among various powders is highest because that powder gave them the least variation and is therefore the most consistent.

There are reasons the manual creators do this. The main one is that they know each lot of powder will vary in burn rate from others and that you are using fixed load recipe's not based on the individual lot number you purchase, and that you rely on it to be safe rather than rely on a pressure test gun to determine your load. A commercial loader has the pressure gun, so he can use it to adjust charge weight to compensate for powder lot variation, but most handloaders cannot do that. Another factor is just erring on the safe side for liability reasons.

So, the bottom line is that published loads may be as much as about 15% below true maximum values. On the other hand, I have three times now run into published minimum starting loads that were already at maximum for the individual gun involved. So you want to start all your load work ups with the lowest load listed, but not be surprised if you can go beyond maximum in some cases, watching carefully for pressure signs. So be conservative and stay safe.


rg1 said:
I've always read that +P loading should be only done with NEW brass and not multifired cases and fired +P cases should not be reloaded again at +P levels.

Actually, that is not a valid generalization. An example: The .38 Special has a MAP of 17,000 psi, and the +P has a MAP of 20,000 psi. Yet, Elmer Keith used the .38 Special case to develop the .357 Magnum cartridge, which has a MAP of 35,000 psi and he successfully reloaded those cases many times and you can reload a .357 headstamp case multiple times, even though most manufacturers give it the same head they give a .38 Special.

You just have to watch your cases and primers for expansion. No way around it.
 
Some of my manuals have the pressures recorded in test barrels and revovlr and pistol length barrels. Some are CUP and some are PSI.
The newer manuals, for the most part do no publish the pressures.
It would be good if they did.
Powder Mfgs are pretty good at keeping one lot the same as the last, If they didn't loads would never be consistent and could be the reason virtually all maximum loads listed way down from the original developed loads, such as the ones developed by Keith. I've heard countless condemnations of the way they measured PSI and even CUP back then. Well..... their loads held up.
It seems all the manuals and mfgs are comfortable with keeping rifle cartridges in the 3,000 to 3,400 fps range, and pistol cartridges well below 1600 fps.
Regardless of powder or firearm used.
 
Again, I'm just asking about +p or maybe a bit hotter.

I also think that the AR platform is a good candidate for this kind of thing.

I get where you're going, but am unsure just why you want to go there. First, a "small" increase doesn't get you anything any animal will recognize, and usually doesn't get you any significant trajectory change, either, and with the increased stress on the gun, why bother??

I don't have a 9mm AR, but I assume its a blowback action, right?
so, second, the blow back action is a carefully calculated BALANCE of factors.

Case pressure, bolt thrust, bolt mass, spring tension and others. Once you start treading above "standard" pressures, you're "off the map, there be dragons here!"

The question is, WHERE are the dragons?? Are they right outside the last line on the map (max data?) or are they further out, where you might miss them entirely?

NO ONE can answer that accurately, because it depends on multiple factors in your rifle and loads.

MAYBE you go "just a little" beyond +P+ and nothing happens. In YOUR GUN. Maybe another gun will have issues at that same point. Maybe your gun has issues at that point, maybe not, there is just no knowing, until you get there, and the dragons eat you, or they don't. ;)

What's the worst that can happen?? Rifle tries to open early, case ruptures, +P+ gas running around inside your action, doing bad things on its way out. Less bad, but still not good, rifle works ok, but the bolt slams back extra hard, every round, Not good for springs, buffer, or bolt group.

If you're a "shoot it till it breaks, then replace the broken parts" kind of guy, fine, enjoy. and keep your wallet handy. Also SAFETY GLASSES!!

If its a "I just want to see if I can do it" kind of thing, fine, and good luck. But, if you NEED more than the max 9mm will do, then you NEED a bigger cartridge, in a gun made for it.
 
Thank you all for your thoughtful replies. I appreciate that you're trying to keep me from doing something dumb.
I asked this question because I was about to start ordering parts for a 9mm build.
I ordered a 10mm lower instead.
Thank you again for your time.
 
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