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 Post subject: Max pressure in LUPs?
PostPosted: Sat Sep 12, 2020 1:18 pm 
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Joined: Tue Jul 14, 2020 4:02 pm
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What is SAAMI max pressure in LUPs for 12 gauge, 2 3/4" shells?




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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sat Sep 12, 2020 1:45 pm 
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That "measure" is no longer used.

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sat Sep 12, 2020 2:48 pm 
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BobK wrote:
That "measure" is no longer used.

So then why is Hodgdon still publishing data with 'LUP' units ?

Oh, right!, - the 'Hodgdon effect', - how quickly we forget.... :roll:

So each time Hodgdon goes with another powder maker for their Clays powder, are we to assume that the new vendor 'verification' process involves old LUP-based equipment ?

....because everyone knows that there's no direct conversion between LUP and modern-equipment 'PSI-based' equipment.

Blast from the past:
https://www.shotgunworld.com/bbs/viewtopic.php?t=202893


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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sat Sep 12, 2020 3:03 pm 
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Yes, it is obsolete, most of us already know that but it is still relevant if you have old LUP data & LUP data is still being published I believe. There are some posts with info & links to articles about it on here. It is truely amazing how many words can be used without actually saying anything useful. Not you Bob, I'm referring to a internet search I just made, but that's another subject. I think the old LUP MAX for 12 ga. is 10,500 LUP . There is no direct conversion. An old guestimate is psi will run about 1000 psi higher than the LUP max. but that is not reliable & doesn't hold in a lot of cases. They are different units based on different systems.


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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sat Sep 12, 2020 3:56 pm 
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geometric wrote:
An old guestimate is psi will run about 1000 psi higher than the LUP max.

But there IS (was?) no 'LUP max' ever published, that's sort of the issue (and the OP's question).


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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 12:06 pm 
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Assuming there is no answer to the question, it raises a couple more: What difference does it make? Would Hodgdon publish a load it didn't think was safe? If the load is in the book, can we assume it's safe?

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 12:17 pm 
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J.Fred_Muggs wrote:
What is SAAMI max pressure in LUPs for 12 gauge, 2 3/4" shells?


https://saami.org/faqs/#lup-cup-psi-preassures

Quote:
For many years gun chamber pressure units had been commonly referred to as “pounds per square inch”, which was not technically correct. The older method of pressure measurement involves a piston through the side of the chamber compressing a lead or copper cylinder in which the measurement of the degree of compression is indicative of the maximum relative pressure generated. With the advent of the electronic transducer, it became necessary to indicate by some means the method and equipment used to determine the pressure values given. This is important, since the pressure values determined by one method cannot be mathematically converted to values for another, despite claims to the contrary. Likewise, the limiting pressure values for the different systems are not interchangeable.


LUP is obsolete.

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 12:40 pm 
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J.Fred_Muggs wrote:
What is SAAMI max pressure in LUPs for 12 gauge, 2 3/4" shells?


I'm not exactly positive, but I just skimmed Lyman's third edition from back when lead units of pressure was in common use. The highest pressure data shown in Lyman's 3rd for 2-3/4" 12ga. is 10,500 lead units of pressure. While this may or may not be maximum pressure in LUP according to SAAMI, it appears 10,500 LUP is within safe pressure.

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 12:51 pm 
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RandyWakeman wrote:

LUP is obsolete.


My yes.

But if you are looking to compare loads from Lyman's 3rd where no psi data is offered then how else can it be done except by using LUP?

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 12:56 pm 
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oldthompson wrote:
RandyWakeman wrote:

LUP is obsolete.


My yes.

But if you are looking to compare loads from Lyman's 3rd where no psi data is offered then how else can it be done except by using LUP?


What is the point of pondering obsolete chamber pressure numbers? Who are you going to send shells to for LUP testing, and why would you bother? SAAMI standards are voluntary in the first place, and just what is there to compare . . . and for what purpose? If anyone wants to know what SAAMI says, just ask them. https://saami.org/ .

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 1:11 pm 
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Well Mr Wakeman, there are several card and fiber loads found in Lyman's 3rd. The pressure for these loads in offered in lead units of pressure. IF a person wants to use "obsolete" card and fiber loads, as some do to prevent plastic litter, the Lyman's 3rd is a suitable source for such loads and in comparing one load to another using Lyman's third that comparison must be made in lead units because as you yourself stated LUP and PSI are not comparable. This reason is incidental to fiber wad loads, but there may other reason to use LUP.


You know MR Wakeman, if I had asked a question about black powder would you answer the question or would you display your ignorance by claiming no such answer exists since black powder is now obsolete? I mean, are you just posting to hear yourself talk or are you the answers expert man?

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 1:35 pm 
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oldthompson wrote:
You know MR Wakeman, if I had asked a question about black powder would you answer the question


Black powder isn't obsolete.

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 1:42 pm 
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RandyWakeman wrote:

Black powder isn't obsolete.


In that case then drams of black powder equivalent is not obsolete either. It is just arcane.

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 1:53 pm 
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Nebs wrote:
Assuming there is no answer to the question, it raises a couple more:

What difference does it make?

Would Hodgdon publish a load it didn't think was safe?

If the load is in the book, can we assume it's safe?

Hodgdon (and otthers?) have published loads that were unsafe, yes.

Various loads have just magically disappeared from the charts over the years.

The issue is, and as I eluded to earlier in this thread, is that Hodgdon is doing a huge injustice to handloaders by not publishing PSI pressure data for their staple powders like Clays.

You can't say that Clays is an "old" powder, and therefore the ancient LUP-based pressure data is still valid (and imply "accurate").

That's total BS....

Clays, as you know has traded hands a few times, reformulated, even moved to other manufactures in other countries.

Are you suggesting that there was no 'pressure testing' validation done on each one of those events ???

If the validation was done, was it done with an old LUP machine, or a new PSI-based machine ?

If the later, WHERE is the (new) PSI-based pressure data ?

I'm sorry, there's simply no excuse, after all that's transpired with the Clays line, that they would be lazy enough to NOT update their reloading data to include current pressure data.

Otherwise, all you have is basically "go/no-go" load data, with them (Hodgdon) saying, "just trust us, it's safe" ...

It's stupid....

If they can't even publish the (current) pressure data (that they have), then they should just take the approach that the Euro's take, and other powder manufacturers of yester-year took, and that is to just publish a "range" of charge weights (like you see with Gualandi wads), and don't even publish pressure.

i.e. Clays: American Taper hull: 'medium' strength primer: plastic wad: 1-oz = [1150-1250 fps]

You can't have it both ways, - publish seemingly "granular" data per "granular" component selection, but then offer it with inaccurate, ancient obsolete pressure data.

It's not a good product, and not a good marketing, and/or business decision (on the part of Hodgdon) to continually do crap like this which continually causes confusion with their customers, which continually causes threads like this (about LUP's), all because of Hodgdon.

The Hodgdon fanboyz can continually carry water for them defend them, and I will still stand by my assertions.


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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 2:18 pm 
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RandyWakeman wrote:
LUP is obsolete.


Hodgdon is still publishing common and popular loads listing LUP.


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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 9:04 pm 
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There was an article in one of the Lyman manuals that said that although LUP testing is no longer used, it is safe to use old LUP data. I have been looking for that article but as of now, I haven't found it.The important thing is it has been tested & found to be safe. Yes, the present system is more reliable. Dogchaser said he thinks it was 10,500 LUPS for 12 ga.. I think Dogchaser is right! Others can do as they please, they usually do anyway, but personally if the LUP numbers look good, I won't shy away from it. There are some old discussions & links to articles on here about it if anybody wants to do some research.


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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 10:24 pm 
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Max pressure with the lead crusher was 10,500 lead units of pressure. For 12 ga. 2 3/4" & 3" loads.

You can't compare lead units to PSI. So there is nothing to get all bent out of shape over.

Both systems give usable results. Some folks don't understand that. Just because the lead crusher system was replaced with the piezo system it does not mean the lead crusher system was inaccurate. That system was successfully used by SAAMI from 1926 until 1992 and no one had any issues with the system.

When piezo came along some loads recorded higher pressures than were shown with the lead crusher. That does not mean that piezo is somehow more accurate, just that that numbers were different and outside of what limits were set for piezo. So some loads were dropped.

Whenever this subject comes up there is a bunch of finger pointing that piezo is right and lead crusher is wrong. Not true. There is no way to accurately compare the two systems. Both have proven themselves.

Lead crusher was replaced because it was slow to use and you couldn't hook it up to a computer, not because there were problems.

IMHO, if I can find the components for a load tested using lead crusher I use it. Everything else is hand wringing over nothing, by people who don't understand the two systems.

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Sun Sep 13, 2020 11:35 pm 
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J.Fred_Muggs wrote:
What is SAAMI max pressure in LUPs for 12 gauge, 2 3/4" shells?

Around 10,500LUP.

Yes, that spec is no longer used, but it also has not ever changed.

Copper Units Pressure (CUP is "no longer used" for metallic either, but it is still specified, because some old cartridges have not yet ever been "converted" to a psi specification.


Also, every one of those pressure specifications are AVERAGES, not absolute hard ceiling limits.
There are some people who get all undie-bunched if a single shotgun shell makes 11,501psi or more, they think it is "ecxessive" or "over-max", which it isn't.

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 Post subject: Re: Max pressure in LUPs?
PostPosted: Mon Sep 14, 2020 6:39 am 
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i just ignore LUP data..
i convert psi to bar and grains to grams, ounces to grams as it is.....

this thread has great mileage.

How many rods to the hogs head ?


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 Post subject: Re: Max pressure in LUPs?
PostPosted: Mon Sep 14, 2020 10:27 am 
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Location: Phoenixville PA
And how many amps per bushel?



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