After the bolt action with a vertical foregrip, and now dropping a .30-06 vs. 308win debate, I'm hoping this isn't a troll, but I'll take a nibble here...

This isn't necessarily true. A .45colt (revolver cartridge) with a 240grn bullet will not have the same stopping power as a .30-06 (high powered rifle cartridge) with a 150grn bullet.

Within a given cartridge, i.e. your chosen .30-06, in general yes, heavier bullets hit harder, for instance a 180grn pill compared to a 130grn, but that's not the whole story. A 200grn pill in the .30-06 eats up a lot of room in the case, and it is a lot slower, meaning it won't have as much total energy, and won't fly as flat, making your job as the shooter a bit more difficult.

To compare different cartridges, or even just different bullet weights of the same cartridge, you can look at it's Kinetic Energy, which is listed in Foot Pounds or Ft.lbs. This is sometimes just listed as "Energy". The more Energy on a given caliber (diameter of bullet), the harder it generally hits.

Another number that I personally put the majority of my interest in is the MOMENTUM of the bullet. Momentum is calculated by bullet weight in grains times velocity in feet per second divided by 7000. Tied to this is the Taylor Knock Out Factor - literally designed to be a measure of stopping power, which is the momentum equation above, times bullet diameter in inches (weight) x (diameter) x (velocity) / 7000. This number explains why a slower, larger bullet will hit harder than a faster, lighter bullet, even if the two have the same Energy. For example, a .45-70 and a .30-06 have similar Energy, but the Momentum and TKO of the .45-70 is much greater, even though it's about 1,000fps slower than the .30-06 (twice the bullet weight, and ~50% more bullet diameter).

More momentum and more energy = harder hitting.

Caliber = diameter of bullet in 100ths of an inch. So a "30 caliber" signifies a 0.30" (30 hundredths of an inch) diameter bullet. However, this is generalized over land vs. groove diameter, and sometimes, not even that accurately.

For example, 44caliber handguns like the 44mag is actually a 0.429" or 0.430" bullet. The .38 Special is actually a 0.357" bullet. The .45-70 Gov't and the .45 Long Colt are both 45 caliber cartridges, but one uses 0.458" bullets, the other uses 0.452" bullets.

Cartridge naming is about half subjective. Kinda like naming trucks. Some of it makes sense, some doesn't. An F-150 Ford, a Dodge Ram 1500, and a Chevy 1500 Silverado all make sense compared to a F-250, Ram 2500, and a Silverado 2500. 2500 is bigger, right? But what do you make of the Lincoln Mark LT, or the Chevy Colorado, Dodge Dakota???

A .300 Win Mag and a .300Whisper are both 30 caliber rifle cartridges, but without knowing something about them, you can't know by the name which one is more powerful. The "300" part gives away that it's a 30 caliber, or 0.300" lands, which would be 0.308" grooves, so a 0.308" bullet, but the rest of the name doesn't give much away.

Then there were older black powder cartridges, like the 45-70 or the 30-30 that were literally descriptive of the cartridge load. The 45-70 was actually named originally the 45-70-405, which meant 45caliber bullet, 70grains black powder, 405grn bullet.

Then there are cartridges like the 30-03 and the 30-06 where the "30" still signifies caliber, but the second part is the date of design. The .30-06 Springfield is a 30 caliber rifle cartridge designed by springfield in 1906.

Then you can get into things like the 22-250 Remington, which is a 22caliber bullet shoved into a necked down 250 Savage case. The 250 Savage was also known as the 250-3000 Savage, which was named that because it was a 25 caliber bullet that could run 3000fps with the original bullet it was loaded for. The 250-3000 Savage was actually a shortened and necked down .30-06 case itself too!

Comparatively, the .30-06 and the 308 Winchester are both 30caliber rifle cartridges, and both use the same bullets. The 308win case is actually designed based off of the .30-06 case, only shortened and running higher pressure. Because of this higher pressure allowance, the 308win can actually produce very similar results to the 30-06, but with less powder, and in a stiffer short action, instead of a long action. The .30-06 gets a slight energy/power edge when looking at heavier bullets, because it can hold more powder, and heavy bullets start to eat into the case volume in the smaller 308win.

Ooh, I almost forgot about "nato designations"... The .30-06 was also known as the 7.62x63mm Nato, and the .308win is also known as the 7.62x51mm Nato. This really illustrates the difference in length of the two cases, 63mm vs 51mm.

HOWEVER, no deer in the world will ever be able to tell the difference between the .30-06 and the 308win.

ALL THAT CRAP JUST TO GET TO THIS PART...

In the .30-06 or the 308win, well constructed bullets in the 150-180grn range will kill any big game species on the North American Continent. You're really only talking about 3 bullet weights in that range, 150, 165, and 180. There are others out there, but those 3 are the most common weights for 30 cal hunting bullets, give or take a couple grains (like some are 168's vs 165's). Both are a little light for bigger bears, moose, or long range elk, but they both have been successfully used repeatedly for this game, and aren't a bad choice at all. Both are a bit heavy for small game like coyotes, but again, they can, have, and will continue to be used for that forever onward.

165 or 168grn bullets get my favor, as they balance the good ballistic profile against weight very well. Heavier built bullets like the Nosler Partition or the Hornady Interbond make great big game bullets. Mid-size game bullets like the A-max, SST, Rem Coreloct, or SGK will produce great results on deer. Lighter built bullets like the V-max, Win BST or SMK make quick work of invading coyotes, albeit a bit messy.

So go with confidence - Remington, Savage, Ruger, Winchester, Howa, Weatherby, Vanguard, Tikka, TC, Stevens rifles in .30-06 or .308win shooting Hornady, Remington, Winchester, or Federal ammo in 150-180grns will kill any deer in the world.