Pipe's a team-fight item to help break base.  Sure it's some survivability, but the value is in the active which applies to all your allies around you and will act as a shield that will block 400 magic damage.

If you're going just straight Treads->Pipe, you've really not build much in the way of survivability items or midgame items in general.

If you want to be more effective, try a progression of Treads->Vanguard->Assault Cuirass.  Bristleback is one of the few heroes for whom Vanguard is a solid item choice (gives you HP, damage block, regen).  Assault Cuirass will help keep you alive to continue doing damage, amplify your damage, and help your team as a whole; the minus armor also applies to towers.

Start with salve+tango+stout shield+2xbranch.  You can get a Ring of Health for your Vanguard from the side shop, and all components for your boots.  If you feel you're hurting for mana, you can grab a Ring of Basilius, Urn or Medallion.  If you're a secondary carry and your team has a melee carry who won't build it, you could build the Basilius into a Vlads.  Keep in mind that Quill Spray damage is physical, so minus armor from AC and Medallion (and Nasal Goo) increases the damage.

Separately, though, equally farmed Ursa's not a hero other melee heros are going to be able to 1v1 manfight against.

Feel free to grab a cloak after Vanguard if you're against a magic-heavy line-up, just don't think you need to rush a full pipe.  I actually only have one game on Bristleback, though thinking I'll get some more in myself.

Anti-mage is one of the more difficult heroes to have success with in an uncoordinated matchmaking game as you're going to want to just farm as much as you can for about 25 minutes before you consider fighting.

An easy aspect of Anti-mage is his build is basically the same every game.  Treads+Poor Man's Shield->Battlefury->Manta->Heart/BKB (one or the other, not both)->Butterfly.

Start off with salve+tango+stout+2xbranch and get a quelling blade with your first 225 gold after that, then finish poor man's shield.  Get an early ring of health for regen in lane, but finish your power treads before the rest of the battlefury.

Battlefury is for flash farming as it gives melee hero's cleave.  Push out your safelane, then blink through the jungle killing camps, then the ancients, push out the opposite lane, ancients again, back through the jungle, back to the safelane.  You can fairly safely split push sidelanes due to your innate escape and survivability from blink and spell shield. Anti-mage is strong because he can farm faster than anyone like this, and gets way ahead because of it, so long as you aren't set way back early, or your team doesn't lose the game before you get the chance to.

Power treads have a technique called "tread switching" where you switch the mode (strength / intelligence / agility) based on what you need at the moment (intelligence before casting a spell to save mana, agility for attacking, strength for taking damage).  Anti-mage is a good hero to get used to this because of the aforementioned flash farming.  Intel treads when blinking, agility when killing camps, strength treads the rest of the time.  If you aren't going to be tread switching, leave them on strength as the HP is the most valuable.

Manta style is the next item because AM uses everything it provides, the biggest being the illusions get mana burn, so they deal farm more damage than illusions on other heroes.  When going for a kill, you can blink on someone, manta, and they'll die very quickly.  Once you have Manta, then you're in a position where fighting is okay, but preferably you want one more item before you're pushing in for the win.

Your primary factor for success is how quickly you get your treads+battlefury.  Key point is not dying so start with blink, get one point in mana break and spell shield and max blink for longer range and shorter cooldown.  Max mana break second as you only need it for kills, and you aren't picking Anti-mage to get kills early.

Normal timings for everything is treads+battlefury at 18 minutes, Manta 5 minutes after whenever you get battlefury.  Aim for 20, but be okay with a 22 minute battlefury.

^ Plus free bonus gold!

The problem with bots is that the harder you make them, the worse your teammate bots are.  So if you try and farm a lot and not dominate the game with kills, your "team" will probably feed to the high heavens.  Then again, that's somewhat analogous to playing with other people.