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Discussion Starter · #1 ·
Can anyone tell me how to convert one to the other. Thanks hunter
 

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Discussion Starter · #3 ·
ok thanks for the link. this is what i'm looking for. maybe not a conversion but there is comparrison. please more info. i know CUP pressures for my guns, but my quick load program list pressures in p.s.i.(piezo). steves site only listed a few. 2 of those help me.
 

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Hunter,
There is no simple mathmatical conversion that I am aware of but I do have a list of pistol and rifle pressures that I have collected, listing pressures. If it will help I will post it here.



Cartridge SAAMI Pressure (PSI)

25 Auto 25000
32 Auto 20500
32 S&W Long 15000
32 H&R Magnum 21000 CUP
32-20 Winchester 16000 CUP
380 Auto 21500
9x18mm Makarov 24100
9mm Luger 35000
357 Sig 40000
9mm Largo 30000
9x23mm Winchester
38 ACP
38 Super (+P) 33000 CUP
38 S&W 13000 CUP
38 Special 17000
38 Special +P 20000
357 Magnum 35000
357 Maximum 40000 48000 CUP
40 S&W 35000
10mm Auto 37500
41 Remington Magnum 36000
44 Russian No standard set
44 S&W Special 15000
44-40 Winchester 13000
44 Remington Magnum 36000
45 Auto Rim 15000 CUP
45 ACP 21000
45 Colt 14000
454 Casull 65000
50 AE 35000





Rifle Cartridges
Cartridge SAAMI Pressure (PSI)

22 Hornet 43000 CUP
218 Bee 40000CUP
222 Remington 50000 46000 CUP
223 Remington (5,56mm NATO) 55000 52000 CUP
222 Rem. Magnum 50000 CUP
22 PPC No standard
225 Winchester 50000 CUP
22-250 Remington 65000 53000 CUP
220 Swift 54000 CUP
6mm PPC No standard
243 Winchester 60000 52000 CUP
6mm Remington 65000 52000 CUP
240 Weatherby Magnum 53500 CUP
25-20 WCF 28000 CUP
250 Savage 45000 CUP
257 Roberts 54000 45000 CUP
25-06 Remington 63000 53000 CUP
257 Weatherby 53000 CUP
260 Remington 60000
6.5x55mm Swedish 51000 46000 CUP
6.5mm Remington Magnum 53000 CUP
264 Winchester Magnum 64000 53000CUP
270 Winchester 65000 52000 CUP
270 Weatherby Magnum 53500 CUP
7-30 Waters 45000 40000 CUP
7mm-08 Remington 61000 52000 CUP
7x57 Mauser 51000 46000 CUP
280 Remington Express 60000
284 Winchester 56000 54000 CUP
7mm Remington Magnum 61000 52000 CUP
7mm Weatherby Magnum 65000
30 M1 Carbine 40000 40000 CUP
30-30 Winchester 42000 38000 CUP
300 Savage 47000 46000 CUP
307 Winchester 52000 CUP
308 Winchester 62000 52000 CUP
30-40 Krag 40000 CUP
30-06 Springfield 60000 50000 CUP
300 H&H Magnum 54000 CUP
308 Norma Magnum 55100 PSI (Norma)
300 Winchester Magnum 64000 54000 CUP
300 Weatherby Magnum 65000
32-20 Winchester 16000 CUP
7,62x39mm 45000 50000 CUP
303 British 49000 45000 CUP (Speer)
32 Winchester Special 42000 38000 CUP
8mm Mauser 35000 37000 CUP
8mm-06 50000 CUP (Speer)
8mm Remington Magnum 65000 54000 CUP
338-06 53000 CUP
338 Winchester Magnum 64000 54000 CUP
340 Weatherby Magnum 53500 CUP
35 Remington 33500 35000 CUP
350 Remington Magnum 53000 CUP
356 Winchester 52000 CUP
358 Winchester 52000 CUP
35 Whelen 52000 CUP
358 Norma Magnum No standard
9,3x62mm No standard
9,3x74R No standard
375 Winchester 52000 CUP
375 H&H Magnum 62000
38-40 Winchester 14000 CUP
416 Remington Magnum 65000 54000 CUP
44-40 Winchester 13000 CUP
444 Marlin 42000 44000 CUP
45-70 Government 28000 28000 CUP
458 Winchester Magnum 53000 CUP

Where two pressures are listed it is PSI followed by the CUP SAAMI pressures. As you can see there places that have the same PSI and different CUP and there are places that PSI and CUP are the same. If you would like an explaination I can provide it.

PaulS
 

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Discussion Starter · #5 ·
This is interesting stuff paul. if you have more to add please do so. you have the .44 mag at 36000psi. i've read the ruger bh is good to 42 or 44000 cuips or psi? very confusing.
 

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Hunter,
The pressures listed are the accepted MAXIMUM SAAMI and ANSI pressures for the cartridge - regardless of the weapon it is fired from. There are some weapons that will tollerate higher than standard pressures but there is no "standard rating" for those weapons. As a matter of interest most +P loads are not recognized by SAAMI or ANSI.

PaulS
 

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hunter said:
This is interesting stuff paul. if you have more to add please do so. you have the .44 mag at 36000psi. i've read the ruger bh is good to 42 or 44000 cuips or psi? very confusing.
hunter,
..... in Lyman's 47th edition. Originally, all pressures were measured in pounds per square inch. Their "crusher" testing and testing still used in many ballistic labs uses a barrel with a hole drilled into the chamber perpendicular to the bore's axis, usually 1" from the rear edge of the chamber A slip-fit piston is fitted into this hole with its end contoured to precisely fit the inside of the barrel chamber. In testing, a cartridge is loaded into the chamber and the piston slipped into place. A copper crusher is then stood on top of the piston and securely held in position with an anvil. When fired, the cartridge case has a small disc rupture from it at the location of the piston hole. The hot and rapidly expanding gasaes in the chamber push equally on the bullet base and on the piston base. The piston in turn moves heavily against the copper crusher, which is forced to collapse to varying degrees depending on the total amount of pressure applied to it by the piston. The amount of "crush" of the copper cylinder is then measured carefully and this crush length is compared to a tarage table which lists a specific value for the amount of crush which occurs. "Copper Units of Pressure". I would stongly suggest that you pick up a Lyman's Handbook on Reloading and read this chapter.
 

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Hunter,
The reason that it is difficult to convert from one to the other is that the copper crushers have a "yield strength" that must be overcome. IT takes a certain amount of force to start deforming the copper crusher - before that there is no deformation (thats why the low pressure loads like shotguns use lead crushers). It also takes time to deform the crusher so a high spike can read the same as a longer lower pressure spike.
The peizo-electric crystal method uses a thin wafer of quartz that produces pressure when bent or stretched. It is attached firmly to the breach of the test barrel and responds to fluctuations as low as 500 PSI in time intervals as low as .00001 second (1/100000).
Both systems use a SAAMI standard pressure round to calibrate and once calibrated the test rounds can be more or less accurately pressure tested. The peizo system is more accurate as to peak pressures and can actually measure the time/pressure curve for a test round in the test barrel. Sadly the crusher method cannot achieve this level of accuracy.

PaulS
 

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Discussion Starter · #10 ·
thats good to here paul. my quickload program uses peizo psi. no do gun manufactures use cups or peizo to rate their guns? please just a litte more u guys have been a big help. :)
 

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Hunter,
The gunmakers use SAAMI pressure test cartridges known as "PROOF" cartridges. They produce higher pressures and are designed to show that the gun can handle a steady diet of "standard pressure" rounds. Cartridge makers and commercial reloaders use test equipment in controlled environment rooms to find the pressures that their cartridges produce with the non-canister powders that they use. As reloaders we use published data for canister powders as tested by the powder companies. I would caution you about data obtained only from computer models due to the large number of variables in cases, powder lots, bullets, free-bore and action strengths. ALWAYS consult manuals (more than one) and begin low and work up in your weapon and under the conditions the ammo will be used while watching for any signs of over-pressure.

PaulS
 

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Discussion Starter · #12 ·
i'm always looking paul. the .45 colt is behind all this. manuals list .45colt loads at 14000. then they list loads for ruger& t/c at about 25000. well i understand the ruger bh(my gun) to be safe to 32000. i think that is cups.
well it looks like peizo psi for 32000 cups would be higher than 32000.
i've come up with some .45 loads that are 32000 peizo psi and i reduced 10% to start with. even at 32000 peizo psi i should be safe in the ruger bh
that is tested to 32000 cups. right ----wrong. paul your really helping me thanks.
 

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PaulS:

I've been looking high and low for that list of Max SAAMI Pressures ... where did you get it (no offense, but this is the kind of data I like to verify!).

I'm looking at loading up some 32acp and I notice that my quickload software says 23,206 for the SAAMI max ... your number of 20,500 agrees with Accurate Arm's published value ... but I also see that Alliant seems to have their MAX loads all come in just under 13,500 psi ... that is an AWFUL lof of safety margin ... don't you think? I was interested in using some V-V N350, but VihtaVuori doesn't list ANY loads for the .32acp :( ... so that's why I'm leaning on the QuickLoad a little more than usual ... I'm thinking that I will start at least 10% below a load that won't exceed the MAX even with a 10% hotter batch of powder, but knowing what that max really is will be a critical part of this process!

The thing that confuses me is that Quickload agrees really well with Alliant's performance and pressure numbers and so I can't see why they would have stopped working the load up ... at least a little higher than 13,500 psi? I am loadign for a Walther PP ... could there be some really weak 32acps out there that might not be up to the SAAMI spec ammo?

Thanks,

saands
 

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Discussion Starter · #14 ·
saands i use quickload also. have found quickload vol. to be very close to croni vol.
 

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Hunter ...

What calibers/powders have you found this to be true with? I'm still investigating, but being close on one doesn't yet give me confidence that it will be close on another!

Thanks,
Saands
 

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saands,
I have compiled the list from published lists in different reloading manuals and sources from a number of sources. I have checked and double checked all the sources however I could. I understand that SAAMI will sell a list but I have not been able to get a response from them.

I have reservations about projections from any interior ballistics program. I am working on adding an interior ballistics routine to my own software and I have found that the margin of error is so high that it gives me second thoughts. A difference in barrel diameter of .0001 is enough to raise pressures 10% when combined with long bullet seating and slight variations in bullet weight, powder charge, and case capacities. With variations in case capacities from brand to brand variations from the norm can be as high as 40%. While these software aids can be indicitive of norms they are not to be relied upon for individual weapons.

PaulS
 

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saands,
the 32 ACP is an extremely small case that is sensitive to minute changes in powder charges. It is likely that loads above those listed gave erratic pressures and or accuracy in the testing. Those are the normal reasons for not developing a load to higher pressures. It might be a fundamental flaw in those powders tested or something in the combination of case and powder combination.

PaulS
 

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There's no conversion. The measurements are made with different kinds of equipment. LUP is the old method, it's being rapidly replaced by PSI as a measurement. Some loading manuals, like Lyman, will publish some loads in PSI and others in LUP. You have to read the fine print.
 

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Pauls:

Thanks for the reply. I don't trust the models to do my testing, either. I will have to say, however, that QuickLoad does seem to give a pretty good approximation of the loads in the books most of the time ... I'll be taking a very conservative load on this one and working up from there with a Chrony and tape measure ... to see how far that brass flies ... of course! :lol:

I did think of another possible reason that Alliant stopped where they did ... the velocity that they obtained at 13,500 psi matches the historical standard of 900 fps for a 71 grain FMJ bullet ... maybe THAT was their goal so they stopped for the day and had a beer. It's not like they are getting hundreds of calls a day for better loads for a silly .32acp!

Thanks,
Saands
 
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