All manuals differ, sometimes quite a bit. Which is "right"? I suspect they all are.

If they all used the same powder lot, same bullets, primers, cases and same rifle they would likely agree pretty closely. But that isn't possible, is it?

Thus, "Start low, only move up....", etc., is the ONLY certain book rule.

Don't feel bad chambered I have one that is copywrite 1971, it doesn't say what edition it is so I suspect it is the 1st.

Your comparison included Lee data and Sierra data. The Lee book cost you $6 and for my money its way over priced. Full of less than useful information and data derived from their interpetation of others data. Sierra actually tests their data and offers loads of free infomation and tips just for the asking. In this case consider the source.

When it comes to loading for a SA rifle I would put function ahead of bullet speed anyday, all day.

Whats really frustrating is if you have books from a single MFG going over many versions, and the loads from the newer books are DRAMATICALLY different from ones in the old books.

I have a couple Hodgdon manuals like that, with a difference in over 300fps in the max load for a particular caliber. If powders are blended with the same burn rate year after year, what could possible cause such a descrepancy in the load information???


-DallanC

DallanC wrote:

Whats really frustrating is if you have books from a single MFG going over many versions, and the loads from the newer books are DRAMATICALLY different from ones in the old books. I have a couple Hodgdon manuals like that, with a difference in over 300fps in the max load for a particular caliber. If powders are blended with the same burn rate year after year, what could possible cause such a descrepancy in the load information??? -DallanC

Load information changes because of too many lawyers,insurance companies/underwriters,and certain reloaders that load beyond their competancy levels.

Take a look at the pressure information that is sometimes available.
Using the 308 Winchester as an example; SAAMI set the limit at 52,000 CUP or 60,000 PSI.
Looking at a Hodgdon basic manual I find the 150gr. B-Tip used in conjunction with H322 only gives 50,500 CUP with a MAX charge of 40.0 gr.
I'm willing to bet you can get a lot more 322 in a 308 case. So the question becomes why limit it to only 40.0 grains.

IMO the answer comes down to the load being useful or not !!!
As you reach a loads MAX it starts to become inconsistent, sure we can run it up more and obtain a higher velocity safely but then we sacrifice the loads integrity. Most re-loaders I know will give up speed anytime they can gain consistency.
It's my opinion that the older manuals reflected this and those that obtain the data know we as re-loaders want the consistency.


Another aspect to this is how things have changed in the industry over the years.
New ways of mixing and formulating powders have actually made them more economical.
As an example talk to anyone that used Red Dot in their shotguns in the 70's. You had to use more of it and it left a lot of unburnt powder and residue in the barrel. Today it's one of the cleaner shotgun powders available.

The other issue - and a big one in my opinion is that - we have a better understanding of the limited information that the copper crusher system of pressure reading and have the better information of the peizo-electric system that displays the entire pressure curve.
Ballisticians have learned that some of the older information actually produced pressures that exceeded the SAMMI maximums. Loads have been adjusted accordingly.
Lawyers have little to do with powder recommendations - those powder companies know that we want total performance and safety in our loads. they also what us around to buy more powder too.

What PaulS said! Better equipment for measuring pressures means safer loads for us. One manufacturer (Speer?) was reshooting its suggested loads and switching all to PSI from CUP.