Maybe you varminters can help out.  I got lucky with my first scope and happened to mount it close enough such that I could rely on internal adjustments.  

Now I've moved to another scope and it's way off... I won't even bother sighting it in until I can atleast get it aligned with the bore.

Thx

Cheapest way: Go to wal-mart, buy a bore-laser-sight-kit (i don't know what it's acctually called) for about $50, Sight in your scope, and return it after you're done...hehehe[:D]

I know on a bolt action rifle you can put the rifle on a rest and take the bolt out and look down the bore and line it up with the target then look thru your scope and see where your at then line them together you should be real close.I never tried it on a AR but it should work if you take the upper off the lower and do the same.

kekozski, Nailed it, simply remove upper and using either sandbags at the range or forearm rest w/ rabbit-ear rear bag, bench the upper solidly, remove bc/b/ch, hold down tight.

Eyeball through barrel and adjust cross-hairs of scope, works well enough to get ya on the paper. Make sure your looking square down barrel and scope, have used this method on many occasions w/ bolt rifles and ARs.

Mike

Start off at 25 Yards if you can just to get it on paper. make sure that you have a large enough target.

ditto, thats what i did when my varminter was too far off to compensate for w/the internal adjstents.  I had to reinstall the rings though, as the way i initially had them installed must have tourqued the scope off to the side..  after i reinstalled and did this style of boresighting, i was out at the range and on the paper within 2" of my target!

Right on. Measure the centerline distance between your bore and scope, and mark the same on a target at about 20ft, the center bull for the barrel, and a corresponding mark above (same distance) for the scope. Mount your scope securely but not permanently, and secure your upper in bags or a benchrest. You can move your whole scope if you have adjustable mounts like Milletts, to make a coarse adjustment. Look thru your barrel and center the target bull in the center of your barrel view. Secure the upper, and then look thru the scope to see if it is on center with the mark for your scope. Then adjust your scope accordingly. You will have to take it to the range for true elevation correction, but should get you well within the ball park (paper). I have used this on all my scoped rifles without fail, and its a whole lot cheaper than a bore sighter.

I think I'll go with the laser-sighter and return method.  

I win! Go me! [:P]

Yeah, but why go to the trouble of acquiring a laser boresighter at all when you can look down the barrel? I feel that the only time a laser boresighter would be needed is on rifles where the is no line of sight down the barrel from the breech end.

I've "eyeballed" many different rifles down the barrels at 25 yards and have ALWAYS hit a standard 8.5" X 11" piece of paper with the first shot.

1. Remove your upper from your lower.
2. Remove the bolt carrier assembly and charging handle.
3. Place the upper on sandbags or in a padded vice about 25 yards from target.
4. Look down the barrel and align the bore with the bullseye.
5. Without moving the upper, gently adjust scope until the reticle is also on the bullseye.

This will get you close enough to start firing and making adjustments.