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I built a 338-06, and I am looking to shoot some cast bullets in it. Using Robert Lee's book, I have converted some loads for other rifles using his pressure and lead hardness formulas, but the 338-06 load section does not have any of the pressure values to use in the formulas. Does anyone have any information on this subject?
First off, cast loads always operate at much lower pressures in that size case, regardless of caliber. That's because if you push them to the same levels as jacketed bullets, you will fill up the grooves of your barrel with lead quicker than you can imagine. 8) You shold also get yourself a copy of Lyman's Cast Bullet Handbook if you don't have one. It doesn't have data for the .338-06, but it has just about everything else and it is much more comprehensive than Lee. Lyman also does their own testing, Lee just uses data from other sources.
Here is a workable and usable formula for figuring reduced loads. I have never used it in a magnum capacity case, only -06 family and smaller, and I would never ever use it with a ball powder. Go to the section in your manual for the cartridge and find the data for a jacketed bullet of the same or slightly greater weight, then choose the powder you want to try.
Jacketed MAX(JMAX) - Jacketed START(JSTART) = Difference(DIF)
JSTART - DIF = Cast START
Work up from there in suitable increments until the groups tighten up. If the barrel starts to lead up before the groups tighten, try another powder. Usually you won't get much more than 1/3 of the way up into the charge table before you get leading.
Cast loads can be very picky about powders sometimes, even when you know the gun likes the bullet. I have watched a 39"(seriously) 5shot 100yd group shrink to under 1" just by switching powders. I generally prefer to use IMR powders for rifle cast loads, usually 3031, 4895, and 4064, but my focus is hunting loads, not target/plinking.
I do have Lyman books, and just about any book on reloading printed in the last 40 years, but they don't have a lot of data on some rifles. If you aren't familiar with Richard Lee's process for figuring out what pressures will work with cast bullets, it is pretty unique. First you get the BNH of the cast bullet lot. Then you find a load with a jacketed bullet in his manual that he has tested and developed the pressure and velocity factors for. The BNH relates directly to a table that gives the maximum pressure for a specific hardness, and within certian parameters you can recuce the loads to achieve a given pressure that will work with a cast bullet. I am always looking for more information to be sure I am not going to get a 'slight bulge' in a barrel.
I shoot a .338-06 with jacketed and recently have begun with boolits as well.
My barrel has seen little action so I had better luck during break in using light loads with SR 4759.
If .338-06 data is not forthcoming, I'd extrapolate between .03-06 and .35 Whelen.
I have the Lee 2nd edition book and like his work as well.
Three 44s