The first, and most probably the most commonly used, is the Khorium Scope. The Khorium Scope is a nice little damage output improver, and unlike its brother Stabilized Eternium, its damage is guaranteed. Khorium adds +12 damage to both your minimum and your maximum damage. Let’s say you had a nice 100 – 200 damage auto-shot–the Khorium Scope would improved it to 112 – 212 damage. Overall the Khorium Scope is a nice steady damage output. Its increased damage is guaranteed, and is obviously the most reliable scope.
The second scope is the Stabilized Eternium Scope. The Stabilized Eternium Scope adds approximately 1.27% crit to all your ranged attacks, and it is the most expensive scope out of the two readily available. The scope itself is destined to cause a critical strike once approximately every 79 shots.
With the knowledge that once in every 79 shots we can expect double damage (a critical strike) on a shot due to the Stabilized Eternium Scope, it has become drastically easier to compare it with the Khorium Scope.
However, the Khorium scope suffers a quite serious flaw, as it would turn out–it only affects your auto-shots. What this means is it only affects your white damage, and half of your shots will not receive the +12-damage bonus.
So let us say you are using a 1:1 shot rotation and you make it to 80 shots with the Khorium scope. Figure 12 X 40 = 480 damage. Either so in other words, you can have 480 damage, or double damage on one of your shots due to your scope with a 1:1 shot rotation. I figure 1:1 is the shot rotation with the most auto shots in the game, so this really is the best case scenario for Khorium Scope.
In reality it all comes down to this: if your crits grant you more than 480 bonus damage, then the Stabilized Eternium Scope is better the Khorium Scope.
However, you must remember Mortal Shots in the Marksmanship tree. Mortal Shots increases damage granted from crits by 30%, meaning that rather than your critical hits causing double damage (your normal shot X 2.00), they will cause your normal shot X 2.30.
All in all, your normal shot MUST hit for more than 480 to match the Khorium Scope, or 336 with Mortal Shots. That being said, unlike the Khorium Scope, the 1.27% crit can also cause crits on your ANY of your shots, meaning it could cause crits on your aimed shot also, which would obviously be more than 480 damage.
All in all, I believe that the Stabilized Eternium Scope is better in almost every aspect. By the time you go into Karazhan, your critical hits should cause AT LEAST 480 bonus damage, especially since most end game builds do have Mortal Shots (20 points into the marks tree for 5/5).
Do you normal shots hit for more than 480 damage (336 damage with Mortal Shots)? If so, get a Stabilized Eternium Scope. If not, get a Khorium Scope.
So we have firmly settled that, for most endgame hunters, Stabilized Eternium Scope gt; Khorium Scope by a wide margin.
However, let me ask you one simple question: does your hunter have 142 hit rating? I am asking you, is your hunter hit capped? If not, then the best scope is Biznick’s 247×128 Accurascope.
How does hitting with your arrows 1.90 percent more of the time sound to you? This is precisely what Biznick’s does for you at level 70.
Overall Biznick’s is still the best scope at level 70 by a long shot (no pun intended), and it simply blows the Stabilized Eternium Scope out of the water!
Think about it, you can hit either 1.90% more or crit 1.27% more. A miss and a crit are pretty much the exact opposite of each other, where a crit multiplies your shots damage by 2.00; a miss multiplies it by 0.00. Even if you have Mortal Shots trained, Biznick’s is still more valuable by a large margin than the Stabilized Eternium Scope.
You might think, “Well 28 crit rating or 30 hit rating… and crit rating will proc my kill command more. Surely Biznick’s is inferior.” However, you are slightly wrong. Hit rating actually scales much faster for a hunter than crit does, and on the shots you don’t miss, you can crit! Therefore, in some ways, a 1.90% increases in chance to hit indirectly increases your chance to crit.
That being said, Biznick’s has some issues of its own. Biznick’s scope recipe only drops off of some of the bosses in Molten Core, 0.1% of the time, and finding an engineer that can do it is a long tedious affair. Also, the mats for Biznick’s are highly annoying to get–especially the lava cores, which are a rare drop on some of the mobs out of Molten Core.
Despite this, Biznick’s is simply the best scope there is, if you are not hit rating capped (142 hit rating without surefooted in the Survival tree, 95 hit rating with Surefooted). If you are hit rating capped, get a Stabilized Eternium Scope.