Re: 338-378 weatherby
I never fails to amaze me that folks will go buy a monster masher round, like the 338/378, then want to shoot groundhog bullets in it. I have talked to the bullet companies and all of them say anything less than the 250, except maybe the Barnes X or Nosler are made for deer, and then if shot from the standard 338 or 338/06. Speed them up and are even less reliable. Elmer Keith designed this cartridge and said to use NOTHING less than a 250 in it. The lighter bullet lose velocity fast (someone here just said that), and lose energy fast too. Speer told me that no knowledgable 338 shooter would shoot anything less than the 250s and the 300s better. I hate to say this, but think a lot of the lighter bullet choice has to do with the recoil going up. But using a light bullet, like the 200-210s in the 338, especially one like the 338/378 akin to shooting 125s in the 300WinMag. Okay if you're hunting ground hogs, but not Elk. Elmer said the test of the load is, can you shoot an elk just forward of the left hip, if necessary, and find the bullet on the right shoulder, or preferably out the shoulder. You won't get a light bullet, regardless of type (maybe the Barnes X, but doubt even them) to do that. If an Elk has a belly full of wet grass and twigs, it will stop almost any bullet coming forward, but the high SD, heavy weights will go on.
I shoot a 338/06 and use only 250s and up, in it. Once you get the heavier bullets moving, they keep moving. One of the reasons we shoot 190s in our 308W in 1,000 yard matches, is, though it only starts at 2550, it is still sonic at a 1000 yds, whereas, the 168s at 2800 lose so much velocity, it is always speculative that they will stay sonic. Once the bullet goes sub-sonic, it is no longer accurate. The heavier bullet also retains energy better too. Obviouly, in my 308 case, a 190 still traveling at 1100 fps at a 1000 yds, is going to have more energy left than a 168 at 1,000 fps at that range, or even at 1,100 fps.
Go with the heavy bullet. The others are play things.