I just bought my first AR style rifle. I bought a Bushmaster target model with 20"bbl (flat top)I can't wait to crank off a few rounds. I found that most people on this site and others liked the Bushmaster so I took the advise and bought it. I do need info on scope mounts for it.What type and height for leupold 3-9x40mm scope. Thanks all.

Congrats on your new rifle! I love mine, I have the A2 version. Can't help you on the scope mounts, I don't have one on mine. Just remember to buy lots of military surplus mags.

You can never, never ever have enough mags.
Remember that most of all.
Besides never having enough guns.
Ooh ! and having enough ammo.
Gotta have that.

OK, don't laugh at this, but---

I remember seeing an ad for Olympic Arms with a flattop AR15 that used Weaver see-through rings(the rifle had 'wood look' furniture on it, too).
No sights to see through to, but, the scope was at a good height and the price of the rings won't kill your budget.
If you want to go shooting ASAP, you might start with this approach.
I'm not kidding.  Get out and get shooting!
This might be the least expensive, fastest and easiest way to do it.
Good choice on the rifle.