Reloading Manuals - Can you really trust them?

[Rockrivr1]

Ok, I'm a bit confused. I'm about to start reloading 357 Mag and am looking at where I should start with my powder loads. What gets me is that I've looked at two different reloading books and they are completely different.

I will be reloading 158gr JHP bullets and using AA#9 for powder. Looking at the latest Speer manual it says the starting point should be 12.3 grns with a max of 13.7 grns. Now, if I look at the Lyman 48th Edition book it says the starting powder load will be 13.4 grns (only .3grns less then the max in the Speer manual) to a max of 14.9 grns. 14.9 grns is 1.2 grns more then the max in the Speer book.

I still consider myself fairly new to reloading so is this normal? If so, what a load of crap. You would think they would be relatively close. According to the Speer Manual, 14.9 grns would be past dangerous.

I guess I'll have to start with 12.3 as the base and work up from there. I'm trying to figure out how you can trust one book over another with such a deviation.

 

[Adam_MA]

Reloading manuals are rarely exactly the same. They test loads using different equipment, and then of course impose their proprietary safety margin.

Your best bet, is to contact the powder manufacture, and ask them directly. In every experience I have had in speaking with different manufactures, I have found the folks to be extremely helpful, and very knowledgeable about their products in a wide range of applications..

 

[jhrosier]

No two guns are alike when it comes to handloading.
The manuals are just a guide to help you establish a safe starting load, from which you will work up cautiously.
Check the manuals to see what gun was used for load developement. Some outfits will use a pressure test barrel or a handgun with a longer or shorter barrel than your gun.
Different brass, primers, and bullets, as well as different seating depths will affect the load significantly.
When the change was made from copper pressure testers to solid state transducers, many of the old loading data was found to have high pressure peaks that never showed up with the older equipment, and the loads were reduced to a safe level.

If you have any doubts as to the safety of a load, get in touch with the powder manufacturer. They will bend over backwards to ensure your safety and satisfaction with thier product.

Handloading is still part art and part science. The art is matching your gun and components to what is given in the manuals.
FWIW, I use the latest Lyman manual as a starting point, and then check the Lee and Hornady manuals, as well as data from the manufacturers website.
I load for dozens of different calibers but I will still ask here or on another favorite forum if I am starting to load a new caliber. I still won't accept unverified data without checking several sources but it is helpful to know what other folks are doing.

Finally, it is not usually necessary to shoot maximum loads. The lightest load that will get the job done is very often also the most accurate and pleasant to shoot.

Jack

 

[Rockrivr1]

Thanks for the information. Didn't even think about the different gun angle. Well, I guess I'll start at the lower range and work up from there. These rounds will mostly be shot out of a Desert Eagle, which needs some umph to cycle the slide. I'm pretty sure I'll end up on the higher end, but don't want to over do it.

 

[M1911]

Start low and move up slowly. I've found that with some powders and calibers, just a .1gr can make a big difference.

 

[Scrivener]

Can you trust manuals? Generally, within the parameters given.

That said, I found an error in Accurate's data for .223 and alerted Accurate to it (it had given the charge range for one powder using another powder's data).

Multiple sources reduce chances of such an error. Always use at least two different sources and make sure you are comparing the same bullet and powder. Extrapolation can be a parlous undertaking (ask me how I know......).

NOTE: Powder manufacturers have on-line data. It makes a great way to verify loading manuals.

 

[highlander]

I don't have my Lyman manual handy but if memory serves me correctly they use pressure barrels for their data for the most part rather than a firearm in the particular caliber.
I have two other manuals and they test their loads in the caliber firearm and pressure barrel.

 

[BIG GUN]

Lyman tells you what their loads were fired in. They also give you the best mix of powders. Hodgdon also has a good manual and breaks down there loads by powder mfgr. If you use a lot of Accurate powders, they have a good one also which includes sections on safe loads for the M1, M14, M1A1, etc. as well as some obsolete calibers.
Well worth buying all three and starting your loads on the lower end and working up slowly.
A chronograph is a great help.

 

[Gammon]

Buy a chrono. It will be one of the best investments you ever make.