LAST EDITED ON Jan-10-07 AT 08:02AM (MST)[p]LAST EDITED ON Jan-10-07 AT 08:01?AM (MST)
Between the two you ask about, I'd go with the .300 Win Mag. I've asked before, but nobody has answered, what the big deal is about the short mags. Accuracy isn't, according to Wieland, as good as the gun manufacturers tout in most cases. Sharper shoulder means more feeding problems, and I simply don't get why people think having a magnum in a shorter, lighter rifle is a benefit. The recoil in a light, magnum rifle is pretty severe. I used to shoot a very light .338 at about 6 1/2 pounds and it wasn't a whole lot of fun. One day, I got some sense and had a 9 lb. rifle built in .338 and like shooting it a whole lot more than the lighter version. With regard to barrel lengths, having a shorter barrel defeats the purpose of having a magnum caliber to begin with. If you want more punch, you need to either go with a bigger caliber or push the bullet faster, or both. A longer barrel will give more velocity per any caliber than a shorter barrel.
If it were up to me for an elk rifle, I'd personally go with a .338 win mag, and not either of the .300s. I had a .300 win mag, and I thought it kicked at least as much as the .338, and I've now got a .300 RUM and I know it kicks more than my .338. Both great rifles and calibers, but for ELK I'd stick with a .338 myself, unless you're limited to only the two choices you asked about, then I'd go with the .300 win mag.
Finally, I agree with "muzz" about not necessarily needing a magnum at all. Even though I shoot a .338 for elk, I realize that many, many more elk are killed with standard calibers than magnums each year. I think if you live in elk country, have plenty of time to hunt and are hunting for meat; more than horns on a shorter hunt where you have to leave to go back home; then a .30-06, .30-338, .338 Federal or .35 whelen might be as good or even better elk calibers than some of the magnums. Sometimes, oftentimes, we all get caught up in "needing" a rifle that will kill elk farther than we'll ever shoot one. Most elk are shot within 200 yards, especially cows and smaller bulls, and you don't really NEED a big magnum to do this at all.