It sometimes puzzles me how necking up a cartridge, i.e. 30'06 to 35 Whelen improves "efficiency." Why are folks able to get velocities from heavier bullets in 35 cal. that would be impossible to get with the same weight bullet in 30'06 without blowing the lid off pressure-wise? Taking it to the extreme, is a straight wall cartridge the most efficient possible?I have not started working up loads for the 338-06 yet, have been studying all of the reloading data I can find though.
At this point I can't see the 338-06 being quite as efficient as the 35 Whelen. I just went through my notes on my .35 Whelen loads. Over the last 6 months I have loaded the .35 Whelen using 17 different powders, 9 different bullets and well over 100 different powder/bullet combos. Only about a dozen loads made it to long range accuracy testing
At the end of the day I did not really end up where I thought I would be with the Whelen. My very best loads were 250gr bullets with Alliant 2000-MR.
65.1gr 2000-MR and 250gr Speer Hot-Cor 2684 fps .65 average
66.0gr 2000-MR and 250gr Norma Oryx 2659 fps fps .80 average
There is lots of info around about CFE223 and .35 Whelen loads. I made a point to compare CFE223 and 2000-MR and the 2000-MR loads almost always outperformed the CFE223 loads for me.
Pushing 2700 with a 250gr pill is serious business in my book. I am only getting 60-70fps more from my .338WM 250gr loads.
Some of you with extensive experience with the 338-06, what is the "sweet spot" for that caliber? As I said above in the .35 Whelen I think its the 250gr bullets.