Considering that a back up rifle will have to fill an unknown role it requires a fairly versatile round. It also helps if this round will perform well with just one bullet loading so the gun doesn’t need to be resighted and a new load developed for each trip. Since this is a rifle that will be used because something has gone wrong with the primary rifle it should be of a popular chambering as the trouble may be the ammunition for the trip did not arrive with the guns. Considering that it is better to have too much gun then too little I think a logical choice for a North American back up rifle is the .338 Win Mag. loaded in heavy for caliber premium bullets. It is ideal for elk and most of Alaska hunting with the exception of being slightly small in some people’s opinions for close up grizzly. It is generally flat shooting enough for most western hunting yet still adequate for the eastern woods. In the south it is generally way oversized, but this is a gun that will only be used if something goes wrong with the primary weapon. Hogs and medium deer will be plenty eatable if the .338 is loaded with tough bullets. Partition type bullets should expand at least moderately to ensure clean kills. The frontal area of even a mildly expanded 338 bullet is still quite large for small creatures. Only as a varmint rifle does it really fail to fill the backup role adequately.

The .338 Win Mag. is the largest of all the chamberings commonly found on ammunition shelves and it can be had in a variety of rifles. These include some good value priced favorites such as the Weatherby Vanguard, Savage models, base model Winchesters, Remington’s and others. If one has a favorite rifle type it is likely chambered in the 338 Win Mag. This has the advantage that the operation of the rifle can be the same as the others in your collection.

Many here suggest the 375 H&H as a great back up rifle, which it is, especially if one considers the world their hunting ground. However 375’s are generally only available on more expensive safari models. The availability of relatively inexpensive rifles, the greater chance of finding ammunition and the slightly flatter trajectory of the .338 likely win out, in my opinion, compared to the 375’s greater knockdown power and slightly more reliable tapered shape, if one is limited to the western continent.

The main disadvantage with the 338 Win Mag is it’s almost 375 H&H quality recoil. Again this is a rifle that will not be used unless something bad happens, but a rifle one can not bare to shoot is useless. In fact, one that someone can shoot but not accurately is worse than useless. The .338 is towards the limit of what many can tolerate but is likely manageable for the majority. Those who find it too much should not try to use it.

If the 338 is too large, what I outlined above is still valid and the logical backup rifle should be a rifle you can handle in 300 Win Mag or 7 mm Rem. Mag., again with heavy for caliber bullets. These rifles make the close in grizzly situation even worse. With this exception most of Alaska, Canada and the lower 48 are adequately covered with either of these.

My vote would go for the Ruger M-77 chambered in .300 Win. When I lived in Alaska 2 popular rounds were the .300 Win and .30/06. Either one will handle what ever walks in North America.

The 338 Win Mag is my favorite cartridge, but if I needed such a rifle as you suggest, (I don't) it would be chambered in 30-06. To be quite honest, Brown Bear is the only animal that would have me "uptight" about the 30-06. It will work on most Grizzlies just fine, unless you happen into one of those 8 footers that occupy about 2% of the Mountain Grizzly population.

A 30-06 with a 180 grain Nosler loaded to 2700 fps is a killing machine.

I suppose it depends what the rifle is "backing up." I've always thought the 270 Win / 338 WM is a great combo. However, I'm inclined to believe more and more that two rifles set up nearly identically and chambered for the same cartridge make the most sense. Anymore I've gone back to the 30-06. It's supremely shootable in a fairly light rifle and get's the job done, period.

While I would like to think of Alaska as some place I could do often it really is too expensive. So for North America I would go with either a 7mm Rem Mag or a .300 Winchester mag as my idea of a backup gun. Wherever I hunt in the west I use one of three rifles and always have 2 of the 3 with me. A pre 64 Model 70 in .270 in a Bell& Carlson classic stack with a 2x7 Leupold scope, a Sako AV 7mmRem Mag with a 3x9 Leupold, or a pre 64 Model 70 in .300 H&H mag with a 3x9 Leupold scope. They are my favorites although I am not sure which is the most favorite although the 7mm has killed the most amount of game. I would probably feel okay with either of the magnums in Alaska if I didn't own a .375.

My primary hunting rifle these days for North America is a .358 STA with a beautiful red walnut stock, and I back it up with another STA with an H&S Precision composite stock. Hopefully I am prepared for any weather and will pick up the rifle that suits the day. Good shooting.

I would say for for the US hunting I would go with the 375 H&H or the 338 RUM. Either could serve as a back up gun. With the 338RUM you can load it up or down in volocity and with the 375 you can shoot down to the 235gr bullet.

Depends on what your primary is, or primaries are. This, of course, depends on what and where you are hunting. Obviously, if you picked your one "real" rifle correctly, the backup should be another exactly the same. If you have more than one rifle you are trying to "back up" with another [BTW, who is carrying this second rifle?], then there must be some kind of compromise, probably in power or flatness of trajectory. I would think that the correct answer is usually .300 Win Mag, but it really depends on the exact question.