Is there a mathmatic conversion?

Specifically, I'm interested in what 50,000 lbs. C.U.P. converts to in PSI and what 52,000 lbs. C.U.P converts to in PSI.

Also, what does 62,500 PSI covert to in C.U.P?

Thanks.

Wow! I just did a search asking this question (after I had asked it here) and found out it has been asked quite a few times. Sorry for the redundancy.

I'm not trying to be too accurate with the conversion and I am not going to load anything based on the coversion. I am just curious as to how many PSI I am shooting when my manual says my load is 50,000 C.U.P., and how many PSI when the manual says my load is 52,000 C.U.P.

From what I can tell in my search, (using Jeffeoso's formula) 50,000 C.U.P equals about 57,500 PSI., right?

Hey GAHUNTER, Don't take this as beating on you, cause it isn't intended as such. My post is to simply alert the Beginners and Rookies that the irresponsible Conversion Formula floating around the net is Full-of-Beans, and can be VERY misleading.

There are multiple problems that prevent the existance of an accurate conversion factor. It has to do with variations in the origins of the C.U.P data a person selects to use, variations in each specific firearm's Bore and Chamber dimensions, and variations in the actual Cartridge Components.

They may create a potential variation of(this is a guess) 5000-8000psi low, or high, or perhaps it is somewhat closer. Too many variables which can cause "Tolerance Stacking" to make even a close guess.

Then the problem can be compounded if a person is trying to use a "Haphazard Strain Gauge System"(Dr. Oehler prefers haphazard) to monitor the BOGUS PSI.

Within this link is verification by Dr. Oehler that there is no accurate CUP to PSI Conversion Factor, nor PSI to CUP.

quote:

Originally posted by GAHUNTER:
I'm not trying to be too accurate with the conversion and I am not going to load anything based on the coversion. I am just curious as to how many PSI I am shooting when my manual says my load is 50,000 C.U.P., and how many PSI when the manual says my load is 52,000 C.U.P.

No way to know, unless the ammo is sent to a SAAMI Lab for actual Pressure Testing.

quote:

From what I can tell in my search, (using Jeffeoso's formula) 50,000 C.U.P equals about 57,500 PSI., right?

Odds are against the value having enough relevance to be useful.

Best of luck to you.

Think of it this way


CUP is an art

PSI is a science

Do you think theres a reliable conversion between the two?

Look for CUP to steadily disappear over the next few years

Hot Core might not agree with this. First I agree that the "equation" floating around will not take your actual CUP reading and convert them to PSI or the other way around. The conversion I have seen is simply an equation for the a line drawn through the data points of a plot for several cartridges having both cup and PSI max listed in various sources.

My view is if you simply wanted to use that equation to say a posted max of "X"cup was closer to 60,000 than 65,000 it would get you in the ball park. If you were trying to say it was exactly 62,350 then there is no conversion. Or if you were wanting to take a "load" with a listed cup and convert it then it won't work. Matter of fact you have no clue that the 50,000cup published for a load is 45,000 or 55,000cup in your rifle.

For my purposes (curiosity) the formula seems to work. Take the .300 Win Mag for example. Using 54,000 as the max allowable pressure CUP and 64,000 as the max allowable under PSI then the formula for cup conversion of 54,000 x 1.51- 17,902 = 63,638 (psi), kinda works.

Like I said, this is not for any use other than when I see a pressure listed in a reloading manual as either CUP or PSI I can equivocate the two in my mind.

The first time I saw the dentonized formula, I knew it wouldn't work - because I'd tried to make a worthy conversion factor long ago. I'd imagine most Reloaders do this too, due to our inherent "curiosity" that GAHUNTER mentioned.

Asking Dr. Oehler to confirm that no accurate converion exists, was simply to have a source that the dentonites would not argue with.

So, the information is out there that the dentonized conversion is misleading and causes folks to draw incorrect conclusions.
---

Best of luck to all you folks.