Your .300 Bee will do just fine. being prepae to take shot to 600 yards is a good idea but odds are you won't have to do so.So I am glad I asked the question as 600 yards seems like a very long shot to me also. I called and spoke with three outfitters who seem very reputable and all three told me I need to be prepared to take shots out to 600 yards (yikes). I told them I was comfortable taking shots out to a max of 400 yards and they indicated it would be better if I practiced out to 600 yards which to be honest, I am not comfortable with. I currently have a Mark V Bee in 300 WBY and thought that would be great for this hunt shooting 180 grain pills but when the outfitters told be 600 yards, I started thinking I needed something different.
Others here have a hell of a lot more experience on elk than I but looking back on what elk hunting I have done most have been 200 to 250 yards or less and if push came to shove I'd say less. One the very few what I consider long range shots I have done, I can count only three. Not in any cchroological order one cow elk at 350 yards with a .35 Whelen. Next one farther out was a Mule Deed at 426 paces. Rifle was a 20" barreled .308 Win.. My all time longest ever shot was another cow elk at 520 yards, laser measured. I'm primarily a meat hunter so choose to hunt cow elk rather than a bull. Rifle ws chambered to the .300 Win. Mag, running the 200 gr. Speer Hot Core pushing close to 2900 FPS. I won't bore you with the details but practice was done over three and a half months prior to the hunt. generally two to three times a week. I'd shoot offhand to 100 yards and from sitting and kneeling at 200, 300 400 or 450 I forget which and 500 Meters at my clubs silhouette range. If the elk I shot had been out at 600 yards, she'd have walked. As it was I almost didn't take the shot. It was about 8AM, no wind and the elk had no clue I was there. It was opening day so they weren't all that spooky. I think that was the only time I've ever wished I'd put in for a bull tag. Rhe herd bull was hige. His antlers were such he could have scratched butt with ease. I do belive that elk could have gone high in the books. No matter. I was happy with my eating meat.
I found out later I could have just as easily used a 200 gr. Partition as it will shoot to the same point of impact as the Speer bullet to at least 300 yards. I never tried it farther out. Just shot some to see how they'd shoot. Good luck whichever way you wish to go.
Paul B.