I'm working up loads for my .338 RUM, and as usual, try to look at sources before I start. The Nosler manual lists 91.0 grs. of H-4831SC with the 210 gr. partition as max. The Hodgdon manual lists 94.5 grs. of H-4831 as max. Is Nosler more conservative, operating at lower pressures, or does the short cut really have that much more ooomph?

Telly

Look at their testing equipment...I'll be they aren't the same...

There is no difference between H-4831 and H-4831SC in burning properties. There is only a physical difference in grain size.

Since the burning rate of a propellant grain is in part determined by its surface area relative to its volume, the short cut granules MAY burn somewhat differently. I do not know what deterrant coating is applied vice the original 4831, but given that Hodgdon gave this powder a new (albeit similar) name rather than simply changing its 4831 production methods to produce all future lots with shorter grains I would be very hesitant to assume that they are completely interchangeable. Of course, the best and only certain way to find the max load is by experiment in your own rifle.

I wondered as Ricciardelli said if they are useing different measuring rigs. More precisely I wondered if Nosler used the electronic pressure measurers and Hodgden copper crushers which tend to allow larger charge weights as the spikes or pressure peaks are taken less account of. Speer has reduced some charge weights as a result of moving from copper crusher to electronic.

Also look at the case brand and primer brand.
Seldom does a manual exactly duplicate a load vs. another manual.

I would think that the SC vs regular cut is the biggest part of the difference. I would not interchange data for the two powders.

The copper crusher to piezo has also changed things a lot.

The percentage difference between the two maximums is well within the difference found in any two chamber/barrel combinations (not to mention variations in powder lots, primers, cases, case preparation, and atmospheric conditions).

Shooters often fail to realize that the data found in loading manuals is only specific to the particular gun, whether conventional production rifle or universal receiver type, which the manual writers used to derive the data. Every rifle is rule unto itself, and data in manuals should only be regarded as general guidelines. While manuals DO tend to be a bit conservative, I have found particular rifles which must use significantly less powder than loads listed as "maximum".

Thanks for the input. I started with the Hodgdon data - starting load & increasing up from there (though I haven't fired any yet) and when I found the Nosler data (which just about maxs with SC at Hodgdon starting point with regular, I got nervous. Old age is hell.

Telly

"every rifle is a rule unto self" wise words and very well put. The more rifles you reload for the more you will see this is true.Manuels are a reference point only, a place to start. You will see over and over in these forums that experienced reloaders advise to "work up slowly" to your max as each gun has it own personality as it were. If you start with book starting points and look carefully for signs of pressure you won't go wrong. A chronograph is a big aid in safe load developement. Again well put Stonecreek.

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Growler