The old 06 has killed every animal on the face of the earth, starting with mice and ending with the elephant. Moose are not hard to kill, it just takes them a while to die no matter what you shoot them with, they just don't realize that they are dead. Brown bear on the other hand would be likely to try and find the person that shot them to have them for a last dinner. Also most outfitters that I have checked with for brown bear want you to bring at least a 30 caliber magnum but there are some that told me to bring what I could shoot well and hit what I was aiming at.
So in the long run if I had only a 06 I would not feel under gunned with it but if I had a .300 Winchester that is what I would use, but then I have a .340 Weatherby so that is my go to gun for dangerous game. Or non dangerous, I just like the way that it shoots, and yes it packs a lot of recoil.
Would a .300 Winchester Magnum be better for moose or brown bear than the old 30-06 ?
To answer your question, yes. Same bullet, just faster and more energy with the .300 WM. Think of the .300 WM as a .30-06 on steroids, or like the difference between a .357 mag and a .38 spl.
Like Critter commented, the .30-06 has killed everything walking on the planet, but for bigger creatures like Alaskan moose and definately for brown bears, there are better choices. The old saying "bigger is better" comes to mind.
But bullet placement trumps everything else, as long as the bullet penetrates into the vitals. Some people cannot handle the recoil of magnum rifles, although there are methods of reducing recoil.
On my first hunt in South Africa, I put a bullet from my 7mm Rem mag through the chest of a waterbuck, but he did not go down. We looked for him for 5 days, and the whole time my PH gave me grief about not shooting enough gun.
On the last evening we spotted the wounded waterbuck and both my PH and I shot, he with his .375 H&H and me with another from my 7mm RM. The waterbuck fell dead. My first 7mm bullet had completely passed through his chest, but it was a little high and just behind his shoulder and did not hit his vitals. My second 7mm bullet went through his shoulders and both lungs. The .375 bullet that my PH shot went through one of the waterbuck's front feet. Bullet placement trumps!!
Glad to hear reasonable talk on here. Seems we are always having the discussion about "enough gun". This past season for example I shot my bull from 363m with my '06 and he dropped. Two days earlier my partner shot his from 250-275 with a 280 AckImp and it took three steps. Shot placement is the key. My '06 is a cheapo Rem 710 and people give me shit all the time. Truth is that it was $300, including the Bushnell scope, but that joker shoots straight and has killed EVERY animal I have shot at. I keep saying I am gonna get a "better" gun but then I look in the freezer or on the wall :) Rifle are like women to me, it is all about taste and comfort!!
First make sure your gun is safe, remove the bolt and clean your barrel from the chamber to the end of muzzle. Clean the barrel using butchers bore shine until a patch comes out white. Run a total of 5 separate patches soaked with denatured alcohol through the bore and let dry for 30 minutes. Insert a cleaning rod with a jag and a dry patch into the neck of the chamber. Make sure it will stay there through the next process. Now using another cleaning rod, install a patch that has been coated...