This seems a very odd comparison to make - a 180 grain 30-06 with a 130 grain 270. I don't know why you'd compare these two bullets which, to me would have such different uses, they certainly wouldn't be expected to perform at all alike. Plus, maybe you do, but I don't know anyone who is very concerned with performance at 500 yards, certainly not with a run of the mill 180 grain slug out of a 30-06. You just wouldn't use that shot.

Let's make a more useful comparison of bullets as well as distances: a 150 grain 30-06 to the 150 grain in 270. From the Winchester site, using Supreme Power Point Plus (only because they have it in 150 gr for both). To me, I would look at how the guns compared at the far more useful and practical ranges of 100 - 300 yards, but I'll put in 500 just because you mentioned it.

150 gr 30-06: 100: 2402 300: 1391 500:757
150 gr 270 100: 2391 300: 1589 500:1016

In my opinion, except at 500 yds, this not very significant, in an apples to apples comparison. And frankly, the 270 is marginal out there as well. You'd really have to look at other factors such as drop (if that happens to be important for your hunts) or having the option of going up to a larger slug if you feel you need it.

Drop (above cartridges)

30-06 100: +1.7 300: -8.0 500 -51.9

270 100: +1.7 300: -7.6 500 -46.6

My opinion? These differences are irrelevant to all practical hunting situations, assuming you practice with and know the guy you're using. I DO NOT BELIEVE that with the drops given, you are going to shoot either at game at 500 yds. 46 inches or 52 inches - I wouldn't touch either - maybe some would, but not often or likely. Therefore, the better (but still marginal) performance of this particular bullet at 500 yards is irrelevant. If you wanted to, you could find either in a bullet (for instance a ballistic tip) that would carry significantly more energy to 500 yards, but the drop would still be quite large, and therefore you wouldn't use it. But if you want to make that comparison, look at a 150 in ballistic tip in both and I do believe you won't see huge differences.

The drop at the more practical range of 300 yds is virtually identical. The 270 does deliver slightly more energy at that range, but both are killers.

You'd have to look at sectional density and what the bullet does to the animal, and again, my guess is little or no practical difference. I suspect you can do whatever you want to whatever game you want at 100 - 300 yds with either cartridge.

Therefore, my conclusion is that the performance of the round at medium weights and practical distances is not the decision maker. Both are excellent, almost equally so. To me, it's whether or not you would want to substitute the option of going ligher, faster, flatter in a 270 (130 gr for instance) for the option of heavier (180, 220) slugs you can get an '06 round in heavier bullets.

Medium slug, medium range - no difference.