Currently, the achievement Sniper Duel is virtually impossible to get. Under normal circumstances, an arrow will not travel 50 meters. You need to be aiming at a specific angle upwards to get it. And that means that you can't be looking at the skeleton when you fire the arrow.
Actually, i've got it ONCE in survival.
The trick it to aim about 3/4 of an inch upward at the skeleton when you are 10 meters taller than it. you will have to do it quickly, or the skeleton might despawn. Finally, pull the bow back all the way.
Anyways, the Acheivements i have trouble with are (in increasing difficulty):
Into Fire: Can never find a fortress
Overkill: You need to kill tons of mobs, and you will fail often to get the right enchantment.
When Pigs Fly: Hard to find a saddle AND get the pig to hit the ground.
On a rail: You need TONS of resources if not in SMP.
Sniper Duel: Skeleton despawn too quick
I have the most trouble with Sniper Duel and On a Rail. I hate laying all the bridges, redstone torches and rails only to find out I was short by about 10 after riding the distance.
Maybe it's mods I'm using, but I can't even SEE a mob 50 meters away on farthest view.
The rest of them aren't all that hard to get.
ok hear me out dup the power rails and just make a really long line straight and just even if stuff gets in your way just knock the block on the ground and one above then keep goingthe hardest one for me is the pig in a saddle thing you have to him up then put the saddle on then dig under just 5 blocks and keep one block on the pig so he stays in place then have your friend knock down the one block and bam call it easy but to me it was really hard and most extremly annoying.
Definetly the end, because you need to get most of the acheivements to actaully get there. You need to get wood and craft a wood pickage, then do the same with stone and iron and diamond. Then you need to get a bucket full of water and a bucket full of lava and start an obsidian farm. Then you go to the nether and find a nether dungeon and kill about 15 blazes, then find your way back and kill many many enderman and then you craft the blaze powder and the ender pearl to get the eye of enders. Finally you use the eye of enders to find the stronghold and complete it. Then you go to the end. You also need a bow, about a stack of arrows, a full set of iron armour and an enchanted diamond sword for the battle.
Getting wood is the hardest achievement? Your not serious, are you?
There's 4 achievements that are difficult for me to do. I can't really decide which one is most difficult though. Also, it's not that difficult to beat the Enderdragon if you have enough arrows to spare. And stay away from the edge of the mainland. I managed to do this on SMP but I almost did this in SSP but I made a really dumb mistake in hardcore mode...
*On a rail: It's not physically difficult, just very time and resource consuming
*Sniper Duel: It's a bit difficult to trap a skeleton but it didn't take me more than 20 minutes to set up/utilize in my hardcore map.
*Overkill: It's tricky to get a good enchantment unless you have a mob farm or do an unreasonable ammount of mob killing. 1.3 will really help this a lot though.
*when pigs fly: If you can't find a dungeon, then this achievement can't be done. Also, it's annoying luring a pig to a narrow ledge I made. Even then, sometimes the pig won't die if you don't calculate how much fall damage the pig can take.