I bought my first .338 Mag. specifically as an elk rifle (too much Elmer Keith growing up). For that purpose it was fantastic using 250 grain Noslers.
After that first trip I began to use 210 grain Noslers to take deer, hogs, one Blue Bull and elk. I love the 210 grain bullets over the 250 grain for almost every use. The 250 grain bullet has exceptional penetration on large game.....more than is typically needed.....and the 210 grain is a bit flatter shooting.
The advantages of the .338 include:
It tends to "hit harder" than smaller calibers. No chambering will result in the same reaction EVERY time, but in general game shot with bigger bore rifles tend to show more reaction to the hit than with smaller caliber rounds. Game shot with the .338 will normally react to the hit better, be knocked from their feet more often, and when they run travel a shorter distance before expiring when compared to calibers of less than .30.
When game does run (and they all will from time to time) the blood trail left by the .338 is much more prolific than with smaller calibers in most cases.
If you ever have the opportunity to hunt truly big game (elk, moose, big bears, buffalo, or any other game weighing 500 pounds or more) you have a rifle that has the power and penetration to handle them with ease (particularly if you step up to a heavier bullet).
Not really an "advantage", but certainly not a disadvantage is the trajectory of the .338. With 210 grain bullets the bullet trajectory of the .338 is basically the same as for the .30-06 or .270 out to 400 yards or so (far as most hunters have any business shooting). This makes transitioning to the .338 easy for those used to shooting .30-06 class rifles.
There are few real disadvantages to the .338, but you can't totally discount a couple of things.
The typical .338 will weigh 1/2-1 pound more than the typical .30-06 class rifle. Part of that weight is because a "normal" .338 rifle will have a longer (24" or 26"....almost certainly no less than 22") barrel than a smaller bore rifle and often that barrel is of a slightly heavier profile. The stock also will tend to be a bit more robust on the .338.
That weight isn't by mistake. While it is possible to build a .338 rifle that weighs in at 7 pounds (or less) by using a 22" pencil profile barrel and lightweight stock, a rifle of that light weight would kick like a mule. At 8 1/2 pounds the .338 is very manageable....but the extra weight "could" be considered a disadvantage by some.
The weight of the .338 is because of one reason.....recoil. This could be the main disadvantage to the .338 (more so for some than others). Make no mistake, the .338 DOES have significant recoil as compared to a .270. It's not the "killer" at the buttstock that some make it out to be, but you definitely know when it goes off. Personally I don't find the recoil of the .338 to be particularly harsh (in a proper weight rifle), but I am somewhat recoil insensitive. I do know several shooters who won't use .270 or .30-06 class rifles because they find the recoil to be more than they want. For those shooters the recoil of the .338 is definitely a disadvantage.
Overall I really like the .338 Magnum. What's not to like, flat trajectory, quick killing, hard hitting and suitable for any game from pronghorn to big bears in a rifle of manageable weight and recoil.
