6.5X55!!!!! I get really excited whenever someone mentions those 4 numbers in that sequence! I personally wouldn't trade my 6.5x55 for anything! If you reload, you will get a lot more enjoyment out of the rifle. For one thing, almost all American manufacturers of ammunition load the cartridge wayyyy down. for another, they almost invariably load it too short. Most of them seat bullets to the cannelure. The rifle really shines when it has:
a.) a long throat
b.)fast twist barrel (mine is a 1:8)
c.) modern powder charges to 52-55,000 psi
If you want modern ammo, you either have to buy European made stuff (Prvi, Norma, etc.) or you can use Hornady's Superformance loads.
My load is fairly moderate, either a 120 Barnes TTSX at 2,750fps or a 140 grain partition at 2,600fps. Here's a picture of my 6.5x55. It is a semi-custom Ruger M77 Mk II with a Burris Fullfield II 3-9
View attachment 206477
A 6.5x55 will take anything in North America, although I would feel better with something bigger for moose and the big bears of Alaska. But I wouldn't hesitate to go after an inland grizzly or elk. The key is to not expect the round to kill quickly beyond 300-400 yards. I never shoot that far anyway as I can almost always get closer once the animal is spotted.
As to expecting a rifle to drop an animal on the spot... I actually started laughing out loud a little. No matter what you hit them with, if you punch even a smallish hole through the vitals you WILL kill them. Cape buffalo were routinely killed with 6.5mm solids through the heart and lungs. Sure you have to track them but most were recovered within a couple hundred yards. The converse is also true. Coyotes hit with a .30-06 still run sometimes, my friend actually hit one (with a .30-06) from 30 feet from his stand last year and tracked it for 175 yards, even though there was lung tissue behind the impact point for 15 feet across the snow, the coyote still ran off. The point is, if you expect a rifle of any caliber, to ALWAYS drop the animal on the spot, I am sorry, you are asking WAYYY too much of a rifle.
6.5x55 has all the killing power you need. If you discount it for elk sized animals (<800lbs) then you would have to discount the .270 as they are almost ballistic twins except the 6.5 probably penetrates a bit better and bucks wind a little better. I know there have probably been innumerable elk killed with a .270 at ranges beyond where I would be comfortable shooting them. If that works, then the 6.5 will certainly due the job if you can shoot under the pressure of that huge 6x6 standing 40 yards from you in dense alpine forest.
Despite all the knowledge to the contrary, people still have a tremendous propensity to blame their rifle or caliber for losing game, or they are just lazy and don't want to track more than 30 yards. Sometimes even incredibly well hit animals run a long way even though their heart and lungs look like jelly. Sometimes they drop on the spot to a seemingly less dramatic wound.
Don't blame the rifle. If you have correctly matched the bullet to the game and sighted in your rifle properly, The rest is up to you. Would I take a steeply quartering shot on a 600 pound elk at 500 yards with one when the light was fading? nope. But if you are willing to wait for a good shot, then it will do the job.
The only caveat I will say is, if you are paying $15,000 for a two week elk hunt and you show up in camp with a 6.5x55, you are really limiting yourself given the short time you have and the massive expenditure to potentially go home empty handed. In that case, I would bring something in the .30+ caliber range. But a 6.5 will do the job on bigger animals if you put the round in the correct spot!
Sorry, rant over.
Pros:
Low recoil and blast
Killing power well beyond what it should be
Penetrates into next week.
Classes up your gun cabinet
sleek, sexy looking shells.
has a heritage
Cons:
There really aren't any if you know where to shoot the animal and more importantly when NOT to shoot the animal.
Pick one up! You will not be disappointed.