Conflicting load data

[ChromeLibrarian]

So what do you do when you have load data from two up-to-date sources that is in conflict.

Example: In the latest Nosler reloading manual the load for the 300 WM, 200gr Nosler Partition, using IMR 7828 is 64gr. - 68gr. The latest Hodgdon data for the same combination of cartridge/bullet/powder is 71gr. - 76gr. That's quite a difference, even for a large case.

How do you decide which is correct?

After all, the starting load from Hodgdon is above the max load from Nosler.

 

[KegCommando]

Take a look at the listed OAL. That is probably the differing factor.

 

[ChromeLibrarian]

Nope. They both list OAL as 3.340".

 

[lonewolf5347]

http://www.nosler.com/index.php?p=15&b=30cal&s=75
here there web page for reloading to double check there powder loads

 

[ChromeLibrarian]

I have the latest books/web pages sitting right in front of me. The data is the same on the web page as it is in the book. Everything has been double checked between the two companies. The fact remains that they give two completely different powder charge ranges with all other known factors being the same.

So who's right? After all, undercharging can be just as bad as overcharging.

 

[Steve C]

I'd start at Nossler's start and work up to Hodgdon's max. Best and most accurate load should be found somewhere in there.

 

[RB98SS]

Primers?

 

[ChromeLibrarian]

Change in primer should not cause the max for one set of data to be 3 whole grains under the minimum for another set of data.

How many of you actually compare data from one source to another?

 

[Claude Clay]

lyman new many loads are different[lower] than the older edition for the same bullet/same LOA/same primer & brass.
newer equals less power. go figure

 

[ChromeLibrarian]

Yes, but in the case I mentioned, both sets of loading data are the latest release by both companies, and there is no overlap at all in the data.

 

[The Bushmaster]

Sounds like you need another loading manual...

This is where a chronograph comes in handy. If you know what the velocity of that particular bullet in that particular caliber is supposed to be. You start low and work up until you reach that velocity or where it becomes the most accurate at a velocity you can live with...

 

[rcmodel]

You want some more?

Lyman #49 shows the .300 Weatherby Mag (or was yours a Win Mag? Can't tell what WM we are talking about?) & 200 Swift A-Frame & IMR-7828 as 78.0 start and 82.0 max!

If it is a WinMag, it shows 70.0 Start - 75.5C Max.

rc

 

[BADUNAME37]

I frequently consult as many different sources as possible when looking to work up a load. I want to be sure there aren't any mistakes that haven't yet been discovered.

As for the OP, I would go in the middle, between the two. Like someone else mentioned, a chronograph would help a lot here, as it would confirm the speeds you are after.

 

[ChromeLibrarian]

It's been pointed out to me that I made a mistake in the Nosler data. The actual data for the 300 Win Mag from Nosler is 70 to 74 gr. vs 71 to 76 from Hodgdon. Makes my example less extreme, but still valid.

How does anyone tell which source is the safest source to use? Nosler says 74 gr is max. Hodgdon says 76 is max. Both have, theoretically done testing.

Lyman #49 shows the .300 Weatherby Mag (or was yours a Win Mag? Can't tell what WM we are talking about?) & 200 Swift A-Frame & IMR-7828 as 78.0 start and 82.0 max!

That I can see. Different bullet designs (more bearing surface/thicker jacket, etc.) cause differences in pressures. Just an example of why you might not want to use the same data for different bullet designs, even if the weight is the same.

 

[rcmodel]

Both have, theoretically done testing.

No, both have done testing.

Just not in the exact same pressure test barrel, with the exact same weather conditions, with the exact same powder lot #, at the same altitude, etc, etc, etc,.

Either set of data would be safe if you start at the suggested starting load and work up, as you always should anyway.

I always compare several different sets of data, and they will never be exactly the same, except for Lee & the powder & bullet companies.
Lee doesn't do any testing, and it will always match something else if you can find who they copied the data from.

rc

 

[ChromeLibrarian]

So, does anyone know if the companies ever compare notes on their loading data? I'd think Hodgdon or Nosler (or any other company) would want to know if someone is recommending their product be used in a way that they have deemed to be not safe.

 

[rcmodel]

All the published load data from all the powder & bullet manufactures are within SAAMI specs, in SAAMI spec test barrels.

Exceptions are calibers actually tested in actual production firearms, for which pressure test barrels are not available in the testing lab.
The tested loads were deemed safe in those firearms.

But some companies are more cautious or consertive when they publish data then others, I'd guess.

rc

 

[NCsmitty]

ChromeLibrarian, although you did misinterpret some data, you had the sense to reach out to fellow reloaders for answers.
rcmodel answered your question on why there are differences between data from one manual to another. I'll add that even powder lot differences can show up in the data.
Lastly, you never can have too much data. Cross checking your information is done by all good reloaders, and that includes using older manuals to show the evolution of powders and loads. I recommend bookmarking different reputable online sites that offer good data.

NCsmitty

 

[Afy]

Quickload is your firend... as are good loading and load testing practises.

 

[Birdhunter1]

I would double check to see which case each is using as sometimes theydo differ.

For an example I took 4 .243 Win cases and 4 Federal cases, loaded them with the same charge, primer and bullet and there is a 50 fps difference.

 

[33rowdy]

Start low and work up and look for pressure! Simple basic Handloading.

But I'd think it would be just simple different testing equipment!

 

[RidgwayCO]

Comparing reloading manuals, downloading and using powder company guides, and using QuickLOAD are all part of the plan for figuring out your starting loads.

But without a chronometer, you're still just guessing...

 

[MCMXI]

But without a chronometer, you're still just guessing...

I hadn't realized how true that statement is until this past weekend. If you're making loads directly from a manual, using the same bullet, powder, primer, barrel length, twist rate etc., you may never need a chronograph. However, if you're reloading for a specific rifle and want the bullet close to the lands, you may not by anywhere near the COL provided in the reloading data so it's really hard to know what's going on without a chronograph. For example, I'm loading the 208gr A-MAX bullet for my .300 Win Mag. The OAL for most of the HPBT bullets around 180gr, 190gr, 200gr and the 210gr VLD is 3.340". For my rifle, with the bullet sitting 0.020" off the lands, the OAL is 3.578" which is 0.238" LONGER than the recommended length!! How does this affect velocity and pressure? Without a chronograph you'll never know. I found that I can add almost a grain of powder to the maximum load listed, but with the extra case volume, I get the same velocity as the max load.

 

[Shoney]

If you will look at each listing of loads, you will note that each probably uses a different weapon (Winchester, or Remington, or Savage, and so on) and different components (primer, case, bullet) in addition to the variation in the powder amount; and they are doing the testing in different parts of the country. What they usually do not list is where they conducted the tests, but geographic location and weather at time of testing factor in.

Combinations of factors can cause great variances in velocity and pressure. Here are a few factors:

Primer: strength, brisance - is a measure of the rapidity with which an explosive develops its maximum pressure
Barrel: length; tightness of bore; height of the lands; temperature of barrel;
Bullet: bearing surface of bullet, alloy of bullet; shape of bullet; distance of bullet to lands;
Brass: new/used elasticity; manufacturer, volume;
Powder: new, aged, old, batch powder was from;
Weather: ambient air temp., barometric pressure, humidity
Elevation: above sea level
Other: I am sure I have not listed all

Now, mix and match them, Care to guess the number of possible combinations?

Use several loading references as a GUIDELINE, and use none as gospel. Do work ups of the loads and watch for pressure signs. They are what tells that you are getting near MAX. not numbers printed in the book.

 

[rfwobbly]

So what do you do when you have load data from two up-to-date sources that is in conflict?

You pick up the phone and call both parties !


Not sure I understand why you are seeking opinions on the internet when you should be seeking facts and answers from the people who wrote the books. I say this because part of the exercise of reloading should be to build complete trust in your manuals... and thereby the products, testing and personnel behind the books. Secondly, if there is an error in the manual, they'll be the most interested to find out about it. Maybe even award you some free bullets.


I salute you on your safety procedures and RLM cross-checking. Good work.