First off, I would like to compare the Edge to the Lapua to clear some things up. First off, the 338 Edge and the 338 Lapua have nearly identical case capacities, generally, which case had the larger capacity depends solely on the brand of brass and even from lot to lot, the advantage can swing one way or the other, for all intent and purpose, they are identical in case capacity.
That said, you take two rifles, loaded to the same chamber pressure with same bullet weight in same length barrels, one in the Edge, one in the Lapua, velocity of each will be nearly identical.
The difference comes in the fact that most will load up the 338 Lapua until they see conventional high pressure signs common with regular cases such as the RUM brass. The lapua brass will not show pressure signs until well into the 70,000 psi range compared to the RUM brass that will start showing ejector rings at under 65,000 psi. Because of this many feel the Lapua is superior in performance when in fact they are simply putting more pressure in the same capacity case for the small advantage they are seeing with the Lapua.
So, for all intent and purpose, with good handloads, there is NO difference at all between the Lapua and Edge class rifles.
Now comparing the 300 RUM w/ 200 gr Accubond to the 338 RUM w/ 225 gr Accubond.
In my experience building dozens of each of these rifles, in a 26" barrel length, you will see 3200 fps with the 300 RUM and just slightly over this, around 3225 fps with the 338 RUM. So again, when both are loaded to the same pressures, velocity is nearly the same. I have seen some 338 RUMs push 3300 fps but its pretty rare to see this without excessive pressures.
Even with that, lets say you get 3250 fps out of the 338 RUM. The 200 gr Accubond has a BC of .595 from what Ihave tested. At least this is what I have to use to get my drop chart to match up with actual bullet drop from many rifles. The .550 BC for the 225 gr Accubond seems to be pretty much dead on.
So right here, from a ballistic stand point, the 300 has an advantage. Slight but it is better with the higher BC. So lets look at some numbers with 200 yard zeros and 10 mph crosswind:
300 RUM w/ 200 gr Accubond at 3200 fps
_________________500 yards_____1000 yards
338 RUM w/ 225 gr Accubond at 3250 fps
Teh differences between the two are so minute that they are well within the shooters margin of error. It would be very hard to say one would be better then the other as far as being able to hit a target precisely at long range.
So lets look a bit deeper and look at the bullets. The 225 gr 338 Accubond has a sectional density of .281. The 200 gr 30 cal version has a SD of .301. That is not a huge advantage for the 30 cal but all else being the same, the 30 cal bullet WILL outpenetrate the 338 bullet, no question, especially when impacting heavy bone. Still, both will easily penetrate deep enough for any big game hunting we will do on this half of the world so again, basically a draw.
That said, on soft tissue impacts, the larger 338 caliber bullet will displace more soft tissue which is the reason they are more impressive terminally at longer ranges. They just move more vital tissues then the smaller calibers. For this reason, on heavier game, the 338 caliber has to be given the nod as it will and is more terminally authoritative then the smaller calibers.
It really comes down to two aspects, possibly three.
What do you need for power. As mentioned that both have plenty of powder for anything you want to do inside 1000 yards with well placed shots. I am not one to believe in the theory that you can use to much gun. There is no such thing as a deader or more dead or deadest animal, dead is dead. Generally the proper bullet selection is the critical part. Some claim that these big guns just destroy game animals. That is not the case. Using a light, hyper velocity bullet is what causes extreme entrance and exit wounds. Us a heavy for caliber bullet with proper construction and there will not be excessive tissue damage. Drive muzzle velocities up over 3400 fps from the muzzle and you get what you should expect, dramatic tissue damage.
For deer hunting, I see no real reason to choose a 338 magnum for a dedicated deer rifle, UNLESS your shooting extreme range, well past 1000 yards or in areas where the wind can be a serious problem or possibly in areas where its very important to drop the animal as soon as possible. For all else, in MY opinion, the 300 RUM is a better dedicated deer chambering then the 338s.
Recoil. Many will say that recoil does not effect them. That is fine, it may be true for some but I have never, NEVER seen a shooter or hunter NOT shoot a very powerful rifle much better when using a muzzle brake
compared to the same rifle without a muzzle brake. In fact, I have seen very few that shot large calibers, 300 RUM class or larger that did not cut their average group size down by at least 1/3 moa when using a muzzle brake compared to no brake. Often its much closer to a 1/2 moa reduction in group size with the brakes. Could they cleanly harvest big game without the brake, certainly but with the brake, their margin of error for shot placement is dramatically increased because they simply shoot the rifles better, they can relax and concentrate on the shot instead of "Piloting" the heavy recoiling rifles.
Plus, a quality muzzle brake allows younger shooters, or ladies or those that are sensitive to recoil (nothing at all wrong with admitting that either) to shoot rifles that allow them to dramatically extend their effective range on big game. I have heard many times that if you need a muzzle brake, your shooting to big of a rifle, BUNK! With todays technology, why not use a brake, no real good reason not to.
Add to that, the ability to use larger rifles. If a new shooter can shoot a 300 RUM just as easily as a 243 Win with the same level of precision, WHY NOT use the larger chambering, especially on larger game.
That said, even with the best muzzle brakes
, you simply can not tame down a 338 RUM like you can a 300 RUM. This is because of a couple things. Bullet weight is one and the other is muzzle gas pressure. This is what makes any muzzle brake work, muzzle gas. The higher the pressure at the muzzle, the more effective the brake will be at reducing felt recoil. The larger the bore size, the lower the muzzle pressure the less effective the muzzle brakes are at reducing felt recoil. This is not to say muzzle brakes are not extremely effective with 338 caliber magnums, they certainly are but even the best designs will reduce the 338s recoil to that of around a 270 Win or 30-06. Not bad at all but to some still to much to shoot accurately. The 300 RUM however can be reduced to that of around the 243 in a sporter weight rifle which anyone with practice can easily master.
Barrel life. I mention this only because its a fact that the 338 RUM has a longer throat life then the 300 RUM. That said, if you heat either of them up, you can burn out a throat in under 400 rounds. IF you take care of both, you will easily top 1500 rounds with either of them.
lets be honest, for most of us, how long would 1500 rounds of barrel life last with our big game rifles, pretty much a hunting carreer and thats with serious big game hunters. For those that do not or can not shoot as much as we usually do, either would easily last several hunting careers!!!
For those that do shoot alot, yes the 338 RUM would get you 500 to 700 rounds longer barrel life but in my opinion is this worth considering the 338 RUM a better choice, not really, the top two considerations would far outweigh this thrid one in my opinion.
So in closing, decide the following:
-Game to be hunted
-Recoil threshold or what recoil you want to put up with
-Is barrel life a real concern or something we just hear talked about
Answer those three questions honestly and it will point you right to the chambering that is best for your needs.