SAAMI vs excess pressure indicators (max load info)

[Jlamont2020]

Is there any known relationship between excess pressure indicators and SAAMI max pressures? I'm curious if there is a rule of thumb sayin' something like pressure indicators usually show up when it's at least 8% (arbitrary amount) or more over max pressure. If not, is there a general rule of thumb of percentage to reduce by when excess pressure indicators are seen?

Long story short, I know what is the minimum needed to function for a custom load, but I believe I need to increase the load a bit to obturate properly. I was curious if there was an easy way of coming up with your max load.

[Case Stuffer]

Long story short, I know what is the minimum needed to function for a custom load, but I believe I need to increase the load a bit to obturate properly.

Pistol,revolver,bolt action,semi auto?

WAG would be semi-auto either pistol or rifle shooting cast BOOLITS but more info almost always helps..

What are the excess pressure signs?

[Outpost75]

Visual indicators such as primer flattening, case head expansion, etc. are not reliable. That is why you use pressure tested load data from a trusted source. Attempting to determine the safety of a load by looking at primers is only a bit more reliable than reading the entrails of a dead chicken in the full moon!

[starnbar]

Running any firearm at the max pressure is only gonna wear out a firearm quicker and if you are shooting paper most of the time why max it out?

[EDG]

First start a load using reliable data so you work up to the hotter loads.
If you start out with a load that is too hot you probably did not start with reliable data and that is not the right way to load safely.
If high pressure shows up it should be because you just passed the lower pressure loads in the work up.

There are no real linear connections between a SAAMI value and just eyeballing a fired case and primer.

Are you talking about case obturation or bullet obturation?
For the case to obturate properly anneal the case mouth.
For the bullet to seal - use a bigger bullet - or a softer bullet. If your bullets are too hard and too small you might see excessive pressure without obturation of the bullet.

Is there any known relationship between excess pressure indicators and SAAMI max pressures? I'm curious if there is a rule of thumb sayin' something like pressure indicators usually show up when it's at least 8% (arbitrary amount) or more over max pressure. If not, is there a general rule of thumb of percentage to reduce by when excess pressure indicators are seen?

Long story short, I know what is the minimum needed to function for a custom load, but I believe I need to increase the load a bit to obturate properly. I was curious if there was an easy way of coming up with your max load.

[Jlamont2020]

Ok, shooting a MiHec 360-640 in 9mm Luger sized to .358 in a Kahr CM9 slugged at .355 and in a Beretta 92A1 slugged at .358. Cast at 20:1 air cooled. Started the load at 2.4gn loaded to 3.4gn where it functioned reliably. I have unfired rounds loaded to 4.5gn but was seeking some info on high pressure. Unfortunately, this is a 100% custom load so there is no load data for this .357 cast HP in 9mm. I've only based it around similar loads. And more specifically I was asking about bullet obturation. I have yet to try any of the hotter loads I made as I wanted some extra info before I decided to work up the load. I don't want to shoot max, but I do want to establish a max for my custom load.

[dromia]

Take your loads to a proof house for pressure testing is the safest way to do this.

[220]

Ive found a very good correlation between velocity and pressure, if your getting significantly above the velocity listed in reputable loading data with the same combinations you can be fairly sure you are also running significantly more pressure.
I find a crohny very useful when working up loads.
Made a rookie mistake developing a load for a mates new rifle, started with listed components and starting load seated to fit magazine without checking the distance to the lands. Rifle was very short throated, projectile jambed into the lands. Showing signs that pressure was high and velocity was nearly 100fps above that listed for the max load.
Pulled up after the 1st shot, checked things and realised what I had done. Seated the remaining projectiles to clear the lands and pressures signs disappeared and velocity very close to the book figures.

[Cmm_3940]

Long story short, I know what is the minimum needed to function for a custom load, but I believe I need to increase the load a bit to obturate properly. I was curious if there was an easy way of coming up with your max load.

Rather than doing this, you should consider using bullets that are big enough to properly fit the bore in the first place. Your accuracy will also improve.

[warf73]

Ok, shooting a MiHec 360-640 in 9mm Luger sized to .358 in a Kahr CM9 slugged at .355( normal rule of thumb is .001" over bore) and in a Beretta 92A1 slugged at .358. Cast at 20:1 air cooled. Started the load at 2.4gn loaded to 3.4gn(what powder?) where it functioned reliably( I would think the Kahr would function at a lighter charge than the Beretta. Moving mass difference). I have unfired rounds loaded to 4.5gn but was seeking some info on high pressure.(from my experiance with auto guns may it be rifle or handgun if you see pressure signs aka primers and such you are way over pressure) Unfortunately, this is a 100% custom load so there is no load data for this .357 cast HP in 9mm. I've only based it around similar loads. And more specifically I was asking about bullet obturation. I have yet to try any of the hotter loads I made as I wanted some extra info before I decided to work up the load. I don't want to shoot max, but I do want to establish a max for my custom load.

I would ask one of the guys with Quick Load to run the numbers for you to be safe.

[Jlamont2020]

Take your loads to a proof house for pressure testing is the safest way to do this.

I would prefer to do this most of all, but my searches online have not been fruitful in finding a company that works direct with handloaders. If anybody knows of a company that tests ammo for reloaders, perfect. I was unable to find any through my internet searches. I was only able to find info on proof testing barrels with 30% over pressure loads, but not ammo testing.

[M-Tecs]

I would prefer to do this most of all, but my searches online have not been fruitful in finding a company that works direct with handloaders. If anybody knows of a company that tests ammo for reloaders, perfect. I was unable to find any through my internet searches. I was only able to find info on proof testing barrels with 30% over pressure loads, but not ammo testing.

Here you go http://www.hpwhite.com/ballistic-testing/

[Litl Red 3991]

Using primers to judge excessive pressure is really worthless. Consider that too much pressure in a 40S&W is 23K+, a 357 is 42K+, and a 380 is 16K + and they all take the same primer. Do you believe the brass in those primers know which cartridge they are in?

Ken Waters had a method of judging pressure "at home" that at least sounded logical. He fired commercial ammo and miked the case "some forward of the rim". He then reloaded the brass with his test loads and compared it's case expansion against the expansion the commercial caused.

[Litl Red 3991]

Is there any known relationship between excess pressure indicators and SAAMI max pressures?

Well, there is a solid relationship between excess pressure and SAAMI pressures. The load recipes that're published were worked up to be as close to SAAMI pressure and then they stopped.

And those excess pressure indicators don't even begin to consider the fact that max pressures for different cartridges aren't related whatsoever and don't come close to showing up reliably for all the different cases sold for each cartridge. A buddy found some really great 9mm ammo. The "great" part was the price. It turns out the stuff passed the "excess pressure indicators" tests and beat the hell out of his favorite pistol, eating recoil springs like candy and finally cracking something inside the sucker. He really liked the brass and was going to keep using it because it was so easy to resize. At the other end of the scale, when I first started reloading for 32mag most of the Federal brass looked like WWI sausage balloons after firing. When I finally found another brand, I discovered why my reloads had been lower velocity than the factory data said was possible.

If you ever weigh brass to find out how "heavy" one brand is versus another, it'll be clear why those excess pressure indicators aren't really very reliable. They might be better if SAAMI also specified wall thickness, head shape and design, hardness and a couple more things to do with cartridges other than exterior dimensions. And then tried to come up with case expansion rules of thumb for every cartridge when they'd settled on those cartridges pressures.

Rules of thumb have a way of blowing those thumbs off.

[EDG]

SAAMI does specify the pressures. There is no point in specifying every little detail in the manufacture of the brass and then NOT measuring the pressure unless you are a handloader or a fly by the seat of your pants manufacturer.
The measuring of the pressure is the only real proof that the pressure is correct.
Even with your examples, bad springs and a cracked part you STILL DON'T KNOW WHAT THE PRESSURE REALLY WAS.
If the ammo is sold in the US it should meet the SAAMI specifications or CIP or both - unless you are buying from source of non-standard ammo. If you are buying non-standard ammo you might get anything.

Well, there is a solid relationship between excess pressure and SAAMI pressures. The load recipes that're published were worked up to be as close to SAAMI pressure and then they stopped.

And those excess pressure indicators don't even begin to consider the fact that max pressures for different cartridges aren't related whatsoever and don't come close to showing up reliably for all the different cases sold for each cartridge. A buddy found some really great 9mm ammo. The "great" part was the price. It turns out the stuff passed the "excess pressure indicators" tests and beat the hell out of his favorite pistol, eating recoil springs like candy and finally cracking something inside the sucker. He really liked the brass and was going to keep using it because it was so easy to resize. At the other end of the scale, when I first started reloading for 32mag most of the Federal brass looked like WWI sausage balloons after firing. When I finally found another brand, I discovered why my reloads had been lower velocity than the factory data said was possible.

If you ever weigh brass to find out how "heavy" one brand is versus another, it'll be clear why those excess pressure indicators aren't really very reliable. They might be better if SAAMI also specified wall thickness, head shape and design, hardness and a couple more things to do with cartridges other than exterior dimensions. And then tried to come up with case expansion rules of thumb for every cartridge when they'd settled on those cartridges pressures.

Rules of thumb have a way of blowing those thumbs off.

[Litl Red 3991]

SAAMI does specify the pressures. ..............

Yes they certainly do:
http://www.saami.org/specifications_...essureData.pdf

And that isn't being questioned or doubted ????

Even with your examples, bad springs and a cracked part you STILL DON'T KNOW WHAT THE PRESSURE REALLY WAS.
..

So you're agreeing that relying on rules of thumb aren't to be relied on ??? thanks

[EDG]

You can specify all the chemical and physical properties of the case to define it exactly but it still does not define the major characteristic of pressure produced by a cartridge. Even if the pistol broke you do not know if the ammo or the pistol or both were defective in some way.

I am saying that a pressure indicators are not reliable unless carefully defined.
In regard to cartridge cases, they can be overloaded to the point that the primer pockets expand.
When that happens all you know is that the brass can not withstand the pressure. You still don't know the actual pressure of the load or if it was excessive for the gun. Soft cases may expand before the pressure limit of the gun is reached but I can tell that the cases are over loaded using pin gauges in the primer pockets and by measuring the case head expansion with a micrometer.
If my cases expand too much, they are being overloaded regardless of the limits of the gun.

Even a blown up gun is not always proof of excess pressure. The gun can be defective too.


>>>It turns out the stuff passed the "excess pressure indicators" tests and beat the hell out of his favorite pistol, eating recoil springs like candy and finally cracking something inside the sucker<<<

Yes they certainly do:
http://www.saami.org/specifications_...essureData.pdf

And that isn't being questioned or doubted ????



So you're agreeing that relying on rules of thumb aren't to be relied on ??? thanks

[Litl Red 3991]

..........
I am saying that a pressure indicators are not reliable unless carefully defined.

Makes sense, however...

I'm suggesting almost the same thing. Only difference is my advice is the present rules of thumb aren't close to being carefully defined or more exactly, they're worthless. They're BS simply because the same rules of thumb don't for example fit both 32Long primers and 357 primers. They're both primed with small pistol primers. Those are going to flatten with some perfectly acceptable 357 loads yet won't flatten with almost double loads in a 32L.

................
>>>It turns out the stuff passed the "excess pressure indicators" tests and beat the hell out of his favorite pistol, eating recoil springs like candy and finally cracking something inside the sucker<<<

That's simply an example of how the rules of thumb PROBABLY failed miserably. In the spirit of the OP's quest for opinions on his query, it was offered as an observation of something that happened when my buddy was relying on a rule of thumb. Those cases looked good to him. Primers looked great.

Are you suggesting the only rule of thumb worth following is to have your ammo proofed by a ballistics lab?

[bhn22]

Even being under SAAMI specs for pressure is no guarantee that you won't accelerate wear in the pistol by shooting heavier than nominal bullet weights for the caliber. SAAMI pressure specs are SAAMI pressure specs, which is 35,000 PSI for 9mm. You can achieve 35K with 80 grain bullets, and you can achieve it with 250 gr bullets, is either optimal? Of course not. When you experiment outside the realm of the known, there are rarely any formulas, bell curves, or graphs to identify what has not been documented yet. Also, you can change to a powder with a slover burning rate, and need to start all over again. I do hope you've considered using a heavier recoil spring in the gun to reduce the potential for any battering. Also, there are multiple weights possible for this bullet, as high as 170ish gr for the solid version. The hollowpoints are what, 145 gr or so? Your seating depth is another wild card too. Nobody here is giving you answers, because nobody here has enough information to do so. If you want to know exact pressures, the ammo needs to be tested. Someone with Quickload might be able to give you more information on starting loads, but even that is not empirical.

[Jlamont2020]

Well, I'm not looking for exact info. I was simply looking for a way to find a max, then a medium load. Cast at 20:1 the boolits are 146gn. I have found the minimum required to cycle my 9mm guns, though just like running at max is not ideal, neither is running at the bare minimum. I think I'm going to do some more research into the percentage increase in powder with similar loads and go from there. If similar loads only increase by 12% (by weight) from minimum to maximum load, I'll consider 10% higher than my minimum to be my max, and will probably never exceed 5% higher than minimum. I contacted the company mentioned earlier about load testing and have yet to hear back from them. In the meantime, seems I need to make a new friend who has Quickload.