Downgrading of Loads in Manufacturer's Manuals

[2000Z-71]

Why do manufacturer's continually downgrade the loads in their manuals? I know that .357 has been downgraded over the years. The rumors that it was do to the perceived "fragility" of k-frames almost makes sense. But why others?

My latest reloading project is 7mm Remington Magnum. Going through two different Hornady manuals, they downgraded the max load of RL-22 with a 175gr bullet by approx. 3.5 grains of powder and over 100fps. Why? My "old" Hornady manual is only about 10 years old and it's their latest where they have downgraded the max load.

The 7mm Mag is a relatively new cartridge, it's not like great grandfather has an old trapdoor springfield hanging above the fireplace that's chambered for it. Had to vent, I just don't understand.

 

[2000Z-71]

Why do manufacturer's continually downgrade the loads in their manuals? I know that .357 has been downgraded over the years. The rumors that it was do to the perceived "fragility" of k-frames almost makes sense. But why others?

My latest reloading project is 7mm Remington Magnum. Going through two different Hornady manuals, they downgraded the max load of RL-22 with a 175gr bullet by approx. 3.5 grains of powder and over 100fps. Why? My "old" Hornady manual is only about 10 years old and it's their latest where they have downgraded the max load.

The 7mm Mag is a relatively new cartridge, it's not like great grandfather has an old trapdoor springfield hanging above the fireplace that's chambered for it. Had to vent, I just don't understand.

 

[44forever]

Too many lawyers. Also, the burning characteristics of some powders have changed over the years and the precesion of the testing equipment has improved.

 

[OFT]

Find a manual that has loads that you like and won't blow up your gun. Use that manual and never look at another one. Then you won't worry about such things.

 

[Paul5388]

Also, the burning characteristics of some powders have changed over the years and the precesion of the testing equipment has improved.

As far as I can tell, none of this is true. The precision of the testing hasn't improved in 40 years of using transducers and the burn rates on the powders I use are still the same as they were 40 years ago.

That's in spite of DuPont moving powder production to Canada and then selling to IMR, who sold to Hodgdon. The Canadian IMR 4350 I have produces within 10 fps of what the old DuPont powder produced.

If you look closely, RL-22 isn't a very consistent powder in terms of tube size. That has to be a factor in the burn rate, since smaller tubes don't burn the same as longer/larger tubes do.

 

[Erich]

In addition to what Paul said, as an attorney, I'd find it difficult to believe that any company would be so stupid as to substantially deliberately change the burn rates of their powders after they'd okayed and published data already for them. Think about the liability that would bring . . .

 

[Paul5388]

I addition to what Erich said, the powder companies go to get lengths to ensure the burn rate is reasonably close to what it's supposed to be for canister powders. That's why they mix and blend until it's right where it's supposed to be.

Alliant still has some 1899 Unique on the shelf that is checked periodically to verify continued performance to specifications. The specifications for their newer batches of powder are the same as they've been for over 100 years.

 

[BillM]

Originally posted by 2000Z-71:
...Going through two different Hornady manuals, they downgraded the max load of RL-22 with a 175gr bullet by approx. 3.5 grains of powder and over 100fps...

Were all the loads downgraded or just the RL-22 loads? Maybe they retested under slightly different conditions and came up with different results and naturally published the more conservative data.

 

[1x2]

Alliant still has some 1899 Unique on the shelf that is checked periodically to verify continued performance to specifications. The specifications for their newer batches of powder are the same as they've been for over 100 years.

I've read a lot (well, I think it's a lot) of stuff for years about changes/no changes to powder and the increased conservatism of published loads, but I've never read this gem. Thanks,

1x2

 

[Paul5388]

The quote was from a Guns & Ammo article,
"Pick Your Propellant
Alliant's got a powder for every purpose.

* By John Haviland
* Posted: 10-28-03"

A Google search for "1899 Unique" will probably bring it up.

OOPS, that wasn't a direct quote. Here it is.

Unique was first manufactured in about 1898 and was one of the first powders Du Pont turned over to Hercules. A jar of Unique powder sits on the shelf at the Alliant Powder plant in Radford, Virginia. The powder in the jar was made in 1899 and still performs to original specifications. "Unique is the oldest and most versatile powder on the market," Quesenberry says.

You do understand "specifications" are not the same thing as "formula"? The formula and/or raw materials can change, but they still have to meet the specifications for burn rate and etc.

 

[canoe on the yukon]

I agree that powders haven't changed.One of the myths that's passed around as a truism is about 2400 being faster than in years past.I've tested 2400 from a batch purchased in the early 70's against a batch purchased in the late 90's.Identical load otherwise and identical gun too,of course.Average velocity was within 10-15 fps.

 

[Paul5388]

There is obviously lot to lot variation and that's due to specifications having a range that will satisfy the requirements, i.e. moisture content 1-50 ppm (that's not a real specification, just an example).

Here's a real formula with a range for several ingredients/chemicals.

A Primex powder contains 0-40% nitroglycerin, 0-10% dibutyl phthalate, 0-10% polyester adipate, 0-5% rosin, 0-5% ethyl acetate, 0.3-1.5% diphenylamine, 0-1.5% N-nitrosodiphenylamine, 0-1.5% 2-nitrodiphenylamine, 0-1.5% potassium nitrate, 0-1.5% potassium sulfate, 0-1.5% tin dioxide, 0.02-1% graphite, and 0-1% calcium carbonate, with nitrocellulose accounting for the remainder.

 

[dennis40x]

Plus or minus 100-FPS/MV isn’t of consequence for most applications with a rifle. The most common big game taken by average hunters are deer. I doubt that the deer notices the difference either way. Out to three hundred yards it is of no practicable significance. I’ve observed over the years shooter competency covering a spectrum of terrible to exceptional. Very few are and were able to achieve the maximum potential from their rifle. During that period of time the charge weight of 57grs of IMR 4350 was reduced to 55grs for a particular load I used. Gentlepeople it mattered not.

 

[NKJ nut]

There is some variation in burning rate from lot to lot but based on what I have experienced powders remain very consistent over the years.

As Paul stated the formula may change but the specifications as to burning rate does not.

 

[myanof]

This same situation happend to me when I bought my new Speer manual 13. I have been loading 158gr 357s at 15.5gr of 2400 for many years and the max in my manual was 15.9gr. Speer #13 now has a max load for the 158gr at 14.8gr. I called Speer and asked them what happened and they said if I have been shooting that old load, and it was approved in a previous manual, it is OK to shoot it in the same guns as previously used. The guy said they make those changes because some foreign guns come on the market that are not built as strong as American guns so they have to dumb down the loads. I have read from others it is because the manufacturer of 2400 made some changes to their burn rate. I listened to the guys at Speer and all has been well.

 

[canoe on the yukon]

Your gun will not suddenly blow up just because a new manual has come off the printing press.

Anyone who lacks the common sense and maturity to carefully work up to a load and back off accordingly whenever any component is changed,probably shouldn't even be reloading.

That said,I've used data from manuals that are decades old with complete satisfaction and see no need to change.

 

[WR Moore]

I noticed a substantial change in charge weight on a load in a Sierra manual. Being curious, I called and asked why. The answer: "Different rifle being used in testing." I also talked with a tech from Alliant, he indicated that if you have no issues in your firearms, the previous load data is safe-I'm paraphrasing, I don't buy his exact quote.

If you think about the number of loads testfired to produce the data found in any given loading manual, you'll realize that they're not using the same barrels for every edition of the manual. There's a guy on another board that used to make test barrels for several companies. They had what amounted to standing orders for certain barrels.

The only issue with using decades old data, is that very occasionally, powders are reformulated and load data does change. I can recall such notices on a couple of different powders, can't recall which. If you're not crowding the ragged edge of safety, it probably doesn't make much difference.

 

[Sunkist]

I agree with what has been said about old loads and best practices. Your cases and especially your primers, will tell you when you've hit the wall and need to back off. My manuals go back to the late 80's. The max loads in some of those should have blown me and my guns to Hades according to some of today's data. If my primers look good and there are no extraction problems I'm good to go.

 

[Skip Sackett]

Your gun will not suddenly blow up just because a new manual has come off the printing press.

ARE YOU SURE?