Fist some background. I usually shoot 168g SMKs out of my .308, but managed to score some 155g Hornady A-Max's. So I started working up loads, referring to manuals, sites etc.
The latest Hornady reloading manual lists:
Varget 35.9 - 44.9 grains IMR 4064 38.4 - 44.9 grains
The Hodgdon site lists:
Varget 44 - 47 grains IMR 4064 43 - 47.5
These are tremendous differences! The Hodgdon site starts Varget .9 grains less than the max load in the Hornady manual and IMR4064 1.9 grains less than the Hornady max.
I will be working up in .4 grain increments, from 41 grains using IMR4064, but this is an arbitrary starting point. I could have started at the low end of the Hornady manual up to the high end of the Hodgdon site, but the span would have been far too wide. Other than the Lawyer factor, why does one think these weights vary so much? One uses a barrel while the other uses a copper crusher? Even if this were the case, I would think they would be relatively close. Pressure is pressure.
My Speer Manual also has charge weights in line with the Hodgdon site, however these are for SMK HPBT bullets, whereas the Hornady is an A-Max. It's a BT but not a HP. I also called Hornady and they said the bearing surface of the A-max was greater than the SMK, but again, it seems like far too wide a difference.
Any thoughts? Anyone have experience with 155g A-Maxs and these two powders? I'd be interested in hearing all of your rational.
Thanks people, and stay safe....
The latest Hornady reloading manual lists:
Varget 35.9 - 44.9 grains IMR 4064 38.4 - 44.9 grains
The Hodgdon site lists:
Varget 44 - 47 grains IMR 4064 43 - 47.5
These are tremendous differences! The Hodgdon site starts Varget .9 grains less than the max load in the Hornady manual and IMR4064 1.9 grains less than the Hornady max.
I will be working up in .4 grain increments, from 41 grains using IMR4064, but this is an arbitrary starting point. I could have started at the low end of the Hornady manual up to the high end of the Hodgdon site, but the span would have been far too wide. Other than the Lawyer factor, why does one think these weights vary so much? One uses a barrel while the other uses a copper crusher? Even if this were the case, I would think they would be relatively close. Pressure is pressure.
My Speer Manual also has charge weights in line with the Hodgdon site, however these are for SMK HPBT bullets, whereas the Hornady is an A-Max. It's a BT but not a HP. I also called Hornady and they said the bearing surface of the A-max was greater than the SMK, but again, it seems like far too wide a difference.
Any thoughts? Anyone have experience with 155g A-Maxs and these two powders? I'd be interested in hearing all of your rational.
Thanks people, and stay safe....