I have been snooping around the site for some time now and want to build an AR15.  I am planning to build a varmit ar15 with a bull barrel for target and small game hunting.  Just have a question for you all.  Do the ar15's have a problem with reliability?  Seems from what I have read they are not too reliable.  Just wanted to get some opinions. Thanks

They are extremely reliable if you dont:

Refuse to clean them.
Shoot them with a barrel/gas tube full of water.
Refuse to use lubrication.

The big key is to not use 5.56 ammo in your .223 match chamber and to use USGI mags.  Other than that all it needs is moderate maintenance.The AR15 is one of the most reliable platforms in the world.  You cant just abuse it like an AK but it requires minimal care to function flawlessly.  

Well, if you consider firing thousands of rounds through an AR-15 until the gas tube melts, and working again when it is replaced unreliable, then yes.  
All jokes aside, the ar-15 is a very reliable platform.  The early reliability problems in vietnam were due to using the wrong type of powder, lack of cleaning kits issued, lack of training and no chrome lining.  Today, all of these problems have been fixed.  I have never experienced a malfunction with my rifle and have used in in some shitty weather conditions.  The rifle when properly maintained is just as reliable as any other rifle.  Keep it clean and use decent ammo and you will experience no problems.  {edit} As stated above make sure you get good magazines, USGI are excellent and i also recommend the british steel SA-80 magazines-what i personally use.  Go to the magazine section of this board and read the sticky about magazine ratings for more information.  Good luck!
-Brian

The only way I would consider the AR16.M16 platform unreliable is if you are in a sandstorm and it gets a nice coating of sand on the internal action - otherwise with good maintenance - there should be no issues at all.

all above are true.
you can't drag it behind a truck and expect it to function.  it likes to be clean and oily and it's hard to keep something oily clean because oil and dirt mix all too well.  So daily cleaning is needed in a battlefield environment.  keeping the dust cover closed is a big part of it.  all machines break, guns jam.  that's just part of life.  i think the payoffs far outweigh the benefits.    

1200 rounds through mine without one problem [:)]

I think one of the biggest payoffs with the AR15/M16 is accuracy. There is arguably no battle rifle in the world more accurate than the M16.

One thing to keep in mind that when you hear of people having problems with the AR, most of the time the rifle has been fired at least a thousand times or thousands of times.  Run any rifle, bolt actions included, that many times and problems will arise.

If you are building a varmit hunting platform you should find it very reliable.  The only time you'll probably shoot it as many times as others here, you'll probably be spending days shooting prairie dogs.  Try shooting a bolt action that many times, you'd probably have problems with it as well.

15000 rounds through my bushy carbine the last 6000 on a new barrel all other parts the same ..no malfunctions.Remember a good AR service rifle should be good for many thousands of rounds as long as you clean and maintain it.