Younggun,
I have owned 4 300 RUM and still own one in a Winchester Mod 70(it was the first one I bought).The .300 RUM is a great round,it has lazer like trajectory,hit's like a hammer and will flat pancake elk.I shot the 180 gr Noslers for years in the one's I've owned and the oneI shoot now sends a 165 Nosler boattail 3300 fps.Sighted in at 300 yds givesme a top of the back hold on elk out to 500 yds if I ever wanna send it that far.I have shot deer,antelope and elk with this round and I have yet to see one do more damage(internal) than this,turns vitals to liquid chunks.
I have also had the plesure of shoot the .338 RUM,now when you touch this Mamoth round off on deer the results are quite humorus,I've seen a Barnes X tear the spine out of a deer where you could fold it in 1/2 and stuff it in a cooler.
BUT.....
all this comes at a price,for bechshooter time at the range with these rounds can be painfull,I can comfotably shoot 20-25 rounds in sitting after that my teeth start to ache.Barrle life is shorter,but probaly if you use it for hunting and occasinal shooting it will last a life time.
Factory ammo is exspensive and alot of places sell out due to the fact that they only stock so much of just a few diffrent weights.
I realy like the .300 Rum and the .338 Rum,you could just about cover all your bases with just these rounds.
What I would realy like to see is a necked down case inbetween the full size RUM(404 J) and bigger then the WSM
and chambered in the .260 size.Maybe somthing called the .260 MUM(Medium Ultra Mag) now that would be beanfeild killer or a .280 with a sharper shoulder could be a .280 SEM(Super express mag).
But all in all we as hunters have about all the avabile chamberings needed,and IMHO the RUM's are at the top.
BBJ