Which book do I use??

[coffeeguy999]

I am using Lyman Cast Bullet Handbook 3rd and 4th editions. I am loading 45-70 Springfield loads and using 405 gr. cast bullets with IMR 4198 powder. Here is my problem. In the 3rd edition loads are 21.5 gr (pressure of 6800) to max of 28.5 gr (pressure of 13900) and when I go to the 4th edition loads are 31.5 gr (pressure of 12400) to max load of 35 gr (pressure of 17700)with the same powder. Now I know they may change up the powder over time, so is that why the loads have changed that much for the same gun? Also the next problem I have is, the powder I am going to be using is also 25 years old. So do I use the old loads (3rd edition) or the new loads(4th edition) with my older powder?

 

[H4831]

Same powder, vastly different loads. The lighter loads are for the weaker Springield trap door models.
All of the loads you quote are low pressure.
Good Marlins should be able to go up to over 30,000. But be warned, they kick like hell at high loadings.
Just look up the Hodgdon site on the net. http://data.hodgdon.com/main_menu.asp

 

[ATOM]

Same powder, vastly different loads. The lighter loads are for the weaker Springield trap door models.
All of the loads you quote are low pressure.
Good Marlins should be able to go up to over 30,000. But be warned, they kick like hell at high loadings.
Just look up the Hodgdon site on the net. http://data.hodgdon.com/main_menu.asp

Agreed. Even at the top end, the loads seem quite low-pressure. The Lee-Enfield action load data inevitably warns of the LE not being able to take high pressure, being able to work with 'only' 40,000 PSI.

Load manuals are always works in progress and changes in loads for the same propellants are common. I would go for the loads in the newest book.

H4831's suggestion WRT Hodgon's site is a good one. I might even suggest calling them and explaining your particular problem.

 

[buffdog]

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Check out the firearm or barrel used to determine the loads. It should say what was used somewhere in the section.

The 45-70 has three different levels. The lowest one for the Springfield, the middle one for the Marlins and similar guns, and the highest loading for the falling block like the Ruger number 1 rifle.

I would use the older edition if in doubt.

Also, check out the method of determineing the pressure. There is a big difference in Lead Units of Pressure (LUP) and Copper Units of Pressure (CUP.)
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