Why wouldn't old data still be good?

[Mr_Flintstone]

Why wouldn't old load data that was developed using copper crushers, for guns that were developed with copper crushers, still be good? It can't be a matter of accuracy. The copper crushers and tools that were available then are at least as accurate as the ones we have today. The only reason I can think of is that somehow the powder formulation has changed over the years. If that is the case, how often does a major reformulation occur that would render previous data obsolete?

 

[GeoDudeFlorida]

Why wouldn't old load data that was developed using copper crushers, for guns that were developed with copper crushers, still be good? It can't be a matter of accuracy. The copper crushers and tools that were available then are at least as accurate as the ones we have today. The only reason I can think of is that somehow the powder formulation has changed over the years. If that is the case, how often does a major reformulation occur that would render previous data obsolete?

Crusher units required interpolation of the results by the lab - testing staff and inspection - and, there was really no way to take materials changes/differences of the copper/lead disks into account. In my experience, the differences are minimal. The primary advantages of using piezo-electric strain gauges are economic, not empiric. Knowing the duration of the peak pressure is nice but the elasticity of the chamber material will be most stressed by peak pressures, regardless of their duration. Crusher units measure peak pressure quite well but, only in a limited area (where the unit is placed) and are only as accurate as the person interpreting the results. Strain gauges remove the human element to a greater degree, but not entirely.


Hope this helps and what I really suggest is that you read up on how each set of tests is conducted and what’s involved with producing informative results from the raw data.

 

[mm93]

I have no idea what a "copper crusher" even is, but I own numerous old Ideal loading manuals from the early 1900's that I get load data from all the time. They're often the best resource I have for my old 1800's single shot rifles loading.

 

[.38 Special]

The bottom line, really, is that the old data still is good, for the most part. I regularly use "old" loads that are above what is now published.

Realistically, that means that some of my loads probably approach or even slightly exceed SAAMI specification, and that the generous safety cushion built into most guns is saving me from myself.

As to powder "reformulations" I sort of doubt that the burn rate of a given powder ever changes significantly, at least in modern times. The lawsuits would be inevitable, and I wouldn't wager on the outcome.

Tl;dr: 70 years ago, pressure testing was a close approximation, the assumption was that handloaders knew what they were doing and accepted responsibility for outcomes, and lawsuits were rare. Today we have pressure testing down to a fairly exact science, the assumption is that a lot of people get into things they have no business doing, and when it turns out badly for them they will sue and win. So the old data is likely no more or less dangerous than it ever was, and as long as you know what you're about, can still be relied upon.

 

[Varminterror]

Why wouldn't old load data that was developed using copper crushers, for guns that were developed with copper crushers, still be good?

In general, data remains to be data, and it's relevance to any specific firearm is tenuous at best... But... for the sake of the over-simplified argument being made:

Are you using powder manufactured contemporary to the data you'd be using? Otherwise, have you done compositional analysis on the contemporary powders and the powder of current manufacture that you'd be using to be certain the new powder aligns with the old data?

 

[Varminterror]

The lawsuits would be inevitable,

Folks like to say this, but it's really not true. Read your manual, it describes an absolution of liability as well as describing a methodology to determine safe loads for individual rifles - some even reference specifically that powders can vary from lot to lot and that firearms DO vary in resulting pressure for a given load, hence the burden is on the reloader.

So in the purest sense, the answer to the OP's question is pretty simple, albeit unsatisfying: The old data didn't really apply to the old powder any more than it does to the new powder. It's known that the old book is only indicative data, just as is the new book, and that the burden remains on the reloader to test to determine the maximum charge for a given powder for their specific firearm.

 

[mcb]

The lead and copper crusher methods of measuring peak pressure are still valid and still in use across the industry. The crusher specifications (copper for cartridges, lead for shotshells) continue to be included in the SAAMI spec. A few of the older more obscure cartridges only have a crusher specification and no one has bothered to generate a transducer specification.

The only problem with old data is if that particular powder changed as some point in its history. Most powders have not but a few powders did changed formulations somewhat and despite efforts to keeps its burning properties the same as the old their usually are some performance changes. This could be an issue using old data with one of these powders if pushing things to the limit. That said the problem is rare, simply due to combination of only a few powder have changed and remained under the same name and the odds these minor changes then result in unsafe condition.

That said with the plethora of data sources out there (many free from reliable sources) the occasions where I use really old data is pretty rare. In my personal case when I do use really old data I run it through Quickloads before I use it to give me some more confidence in using the old data. And as always start low and work up to the desired velocity.

 

[Captain*kirk]

One of the biggest reasons is that many of the components used to built those loads have changed or are no longer available. You might still be able to get, say, a 7mm 160gr SPBT bullet, but now it may be without the cannelure, or a 'new design', or from a different manufacturer altogether. Tiny changes multiplied several times can add up.
That being said, all things considered, if I can get the components as listed, I still use tried-and-true load data for pet loads.

 

[Otto]

Why wouldn’t old data still be good?

The same reason Hornady no longer provides 9mm load data for Super Target.
In fact, nearly every edition of Hornady’s load manuals contain inaccuracies. Current load data insures safety.

Handbook Errata - Hornady Manufacturing, Inc

Below are errata pages for past publications of the Hornady® Handbook of Cartridge Reloading. Please print the appropriate errata for your edition and insert in the publication so you’ll have the correct information. We apologize for any inconvenience...

www.hornady.com

 

[jmorris]

I don't know, I use old data all the time. I have powders on hand where there is no "New data" available.

 

[GeoDudeFlorida]

nearly every edition of Hornady’s load manuals contain inaccuracies.

Including the current one?

Current load data insures safety.

Ibid.

 

[GeoDudeFlorida]

I don't know, I use old data all the time. I have powders on hand where there is no "New data" available.

The one thing we know about old manuals and the loading tables they contain: those loads have been tested by time and hundreds, or perhaps thousands, possibly even millions, of independent testers with documented results.

It’s up to us to find their documentation and judge it for ourselves.

 

[.45Coltguy]

Folks like to say this, but it's really not true. Read your manual, it describes an absolution of liability as well as describing a methodology to determine safe loads for individual rifles - some even reference specifically that powders can vary from lot to lot and that firearms DO vary in resulting pressure for a given load, hence the burden is on the reloader.

So in the purest sense, the answer to the OP's question is pretty simple, albeit unsatisfying: The old data didn't really apply to the old powder any more than it does to the new powder. It's known that the old book is only indicative data, just as is the new book, and that the burden remains on the reloader to test to determine the maximum charge for a given powder for their specific firearm.

Then, it's still a good idea when using a different lot of a said powder[IMR 4350 as an example only], to start at a known manuals start data? Wouldn't that be playing it safe?

 

[Varminterror]

Then, it's still a good idea when using a different lot of a said powder[IMR 4350 as an example only], to start at a known manuals start data? Wouldn't that be playing it safe?

A lot of folks DO rework loads when changing lots of powder. I know a lot of folks also do not start at the starting loads in the manuals even for their first load developments, but many folks do back down from their pet load and re-work their loads when changing lots of powder.

But while I generally agree, that is "playing it safe," I'm not necessarily sure it's really "playing it safe." The MAP used to establish max loads in reloading manuals is only true for the barrel they used, so we may actually be above or below that pressure with our specific, individual barrels even without the complication of changing lots. Equally, SAAMI Standards include more than just MAP - the Maximum Probable Lot Mean and Maximum Probable Sample Mean are higher pressure than the MAP, meaning that a lot of ammo may not be "out of compliance" if a sample from the lot tested at a higher pressure than the MAP. And finally, of course, pressures don't spike dramatically and immediately if we exceed maximum loads - so combining those two realities: We may find ourselves unwittingly above SAAMI MAP even with a charge weight below the book listed maximum, or we might slide even a half grain or more above MAP and above book maximums without actually seeing or feeling any significant signs of pressure increases.

We get caught up in believing that if the book says 55.8grn of a powder is max, and we know that cartridge has a SAAMI MAP of 55,000psi, then 55.8 must produce 55,000psi and 55.9 would be dangerous... But in most cases, we really just don't know if any of that is true, for the good or the bad.

 

[GeoDudeFlorida]

Then, it's still a good idea when using a different lot of a said powder[IMR 4350 as an example only], to start at a known manuals start data? Wouldn't that be playing it safe?

In General, load work ups start at the starting load and work up to the most accurate load that meets a particular need - velocity for expansion, energy for ethical hunting, etc. Once a good load range is established, a lot change won’t require a from-scratch build, just drop back to a last known-good minimum (which you established during load workup) and if the velocities are lower than the previous lot, go up until you find a best, most accurate load; or, work down if the velocities are higher than the previous lot.

Lot-to-lot variations are typically pretty small. I have a habit of checking the volume-density of new lots of powders against past lots to see if they’ve gained or lost density. A more dense powder will reach the same weight at a lower volume - and vice-versa - but that really hasn’t had any observable relationship to load performance in my experience. But it’s easy to test for yourself and I encourage that testing.

 

[AJC1]

The minimum and maximum charges are just guardrails to keep you coloring inside the lines. Each test is just that a series of tests, and groups of data are not the same when compared to each other. The most valuable piece of data to me is the start charge. Where to begin and go from their. The units don't make one bit of difference to me. How that charge performs in my firearm matters most, and if I start getting sticky extraction before their listed max I'm still done....

 

[jmr40]

We get caught up in believing that if the book says 55.8grn of a powder is max, and we know that cartridge has a SAAMI MAP of 55,000psi, then 55.8 must produce 55,000psi and 55.9 would be dangerous... But in most cases, we really just don't know if any of that is true, for the good or the bad.

Sometimes, most of the time in fact, the max load listed is simply where the manufacturer stopped testing. Many times, other, or newer manuals show a heavier charge as max. Somebody else tested with a heavier powder charge and determined it was safe to do so.

 

[Mr_Flintstone]

Crusher units required interpolation of the results by the lab - testing staff and inspection - and, there was really no way to take materials changes/differences of the copper/lead disks into account. In my experience, the differences are minimal. The primary advantages of using piezo-electric strain gauges are economic, not empiric. Knowing the duration of the peak pressure is nice but the elasticity of the chamber material will be most stressed by peak pressures, regardless of their duration. Crusher units measure peak pressure quite well but, only in a limited area (where the unit is placed) and are only as accurate as the person interpreting the results. Strain gauges remove the human element to a greater degree, but not entirely.


Hope this helps and what I really suggest is that you read up on how each set of tests is conducted and what’s involved with producing informative results from the raw data.

I’ve been reading up on this for quite a while now, and it is a fascinating subject. I started with a 1921 Bureau of Standards ( https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT185.pdf ) paper to get a better understanding of copper crusher testing in its relative infancy, and then branched out. Not much has changed since the early days except now we have piezoelectric transducers to more accurately and directly measure pressure curves. Lots of reloading manuals are still using data from many years ago in CUP measures for loads in various older cartridges and powders. I even emailed Sierra once to ask about some of their loads in older manuals, and received a reply that said they don’t really retest older data except when they have discovered an error, and only update existing data with newer cartridges, bullets, and powders.

The same reason Hornady no longer provides 9mm load data for Super Target.
In fact, nearly every edition of Hornady’s load manuals contain inaccuracies. Current load data insures safety.

Handbook Errata - Hornady Manufacturing, Inc

Below are errata pages for past publications of the Hornady® Handbook of Cartridge Reloading. Please print the appropriate errata for your edition and insert in the publication so you’ll have the correct information. We apologize for any inconvenience...

www.hornady.com

Any data is only as good as the human measuring, compiling, or using it. A breakdown at any or all of those three points could be catastrophic. Speer number 8 is a good example. They put in probably the hottest (more than likely way over pressure) data I’ve ever seen for lots of cartridges, and had to put warnings in later editions. That’s why I keep several load manuals to cross reference. Lately though, I’ve just been using GRT to check loads. Common sense is a necessity when cherry picking data. Any data that promises 1200 fps from a 158 gr bullet out of a 2” 38 Special is going to set off some red flags.

 

[243winxb]

Why wouldn't old load data still be good?

Different manufactures, in differennt countries. *Accurate No. 9.*

Even todays modern powder/data may not work when tnere is a difference in lots of 10%
https://apps.dtic.mil/sti/citations/ADA572333 H4831 powder.

 

[BBarn]

Never seen any publishers of data recommend the use of their older data, if desired, in place of their current data. Old data may be all that's available in some cases, but that doesn't mean it's still recommended. I guess if you use old data, YOYO.

 

[Mr_Flintstone]

Different manufactures, in differennt countries. *Accurate No. 9.*

Even todays modern powder/data may not work when tnere is a difference in lots of 10%
https://apps.dtic.mil/sti/citations/ADA572333 H4831 powder.

And IMR 4227; Australia and Canada. They were close, but not the same,

 

[Otto]

If you’re using powder that’s been discontinued, old data is your only choice..in my case that would be PB, Super Lite, Nitro 100 and a couple of others.

 

[Mercy Me]

Because new data are more accurate, it’s all about improvements

 

[Walkalong]

Some of the old data was the testers stopping when they saw "pressure signs", which better pressure testing equipment/methods later showed to be faulty.

 

[jmorris]

If you’re using powder that’s been discontinued, old data is your only choice..in my case that would be PB, Super Lite, Nitro 100 and a couple of others.

If your powder was produced when the (old) data was compiled, and we are to believe something has changed, wouldn't new data (if available) be suspect?

Discontinued or not, if its as old as the data...