Why am I smiling? This is what trigger-happy looks like!

Shrapnel is a slow and grants vision there's no reason not to get it before level 6 as it will guaranteed help you get assassinate off on those jukers. Furthermore if you're getting shadow blade just as an escape, then you've just wasted 3000 gold, sniper has long range to help him keep at the back of the fight, if you're finding yourself in the middle and getting focused on it means your positioning is wrong and a shadow blade is not going to help you there.
Also how is medallion not in your items? It grants you both armour and armour reduction on enemies for FREE and since sniper both needs armour and damages mainly with auto attacks this it too good an item to pass up. For 1000 gold it's such a good item it's not even funny.

Manta Style is one of the better items on Sniper. It gives +10 to all stats (the health is much needed), the agility is great on him, it gives movement speed for added survivability, and you can dodge stuns/diffuse yourself of some spells with the active, AND the illusions can headshot. I don't like that it's not core, or even in situational.

Try Ring of Aquilla into Phase Boots and finish with Drum of Endurance before you get your lothar's.
Lothar's is an expensive item that can be countered so easily if the other team knows what they're doing. I still pick it up everytime I play sniper, but the stats and move speed that comes from the combo I mentioned can be a life saver if the other team has any form of detection.
Oh, and get at least one point in shrapnel before level 6... The slow is actually good, but you get for the vision it provides over the area, so you can farm/push safer. It can actually be good for getting Assassinate kills, because of its long casting range, you can cast just to get vision on that fleeing enemy and ult him

Well, i think that getting lifesteal is a total waste on him, cause he doesn't have much health to spare to begin with. In my experience, sniper is either bursted down first, or not hurt at all during the teamfights. Removing the lifesteal, i do the same build, except that i rush Shadow Blade even before my boots. No +1 from me though.

Well its not easy to win with sniper, if your enemies know how to handle him.
Mask of Madness is not really good on him. it just leaves you as a oneshot for many heroes.

I also dont really agree with crit as core. IAS works so much better, because of Perma headshot stuns. Mjollnir + Manta is the build i keep using on him. Gives you a lot of headshots and AOE damage.

But as mentioned above, I dont like Sniper at all, he is countered way too easy and even with Shadow Blade you are an easy target, if just one enemy got dust or maybe even gem.

Also many melee carrys can just jump right into your face, wich mostly means you are dead (e.g. Faceless Void, Anti-Mage, Chaos Knight, etc)

Before boots or anything i rush shadow blade then go farming you can easily run around to any lane farm up kill a few heroes quickly knock a tower down and run to another and repeat,the mistake people make with sniper is they try to fight in melee distance,i personally wait till the fight has started then pick of the weakest just with my normal shot then ks when someones on the run.

He s a very very easy hero to win with if your prepare yourself and position yourself right don't be afraid to run away and get out of range then re position yourself again.

also i would go for desolator to knock down towers quicker due to the armour reduction and mjollnir for farming i usually have so much money left over from him i dont manage to spend it all.also i only put my points into shrapnel if i have to its a pointless skill that does next to no damage nice guide i wouldn't use it but plus one for u!