I assume you are referring to barrel twist and not some demented government gun demilling process
Twist is the rifling/grooves cut into a barrel during manufacturing process to stabilize the bullet in flight. The barrel twist is basically the amount of spin your firearms barrel will put on the bullet as it travels through the barrel. It is a very important thing related to accuracy of your firearm. The AR15 style rifle can have very different barrel twist depending upon caliber, barrel length and grain of bullet. The twist can actually make the bullet travel faster or slow, but there are limits and consequence to these changes too.
A bullet that is fired with the wrong twist can actually make the bullet do things like fragment in flight before hitting the target. Another little know fact is that a 10" barreled or less AR with about a 1/9 twist, firing a standard 5.56 LEO rd (not military) will generally have less penetration that a 9mm fired from an H&K MP5.
Most standard 16" barreled AR15's you find here in the states will likely have a 1/9 twist, simple because it fires the largest range of bullet weights without overly affecting accuracy when you goto extremes. 55 and 62 grain bullets are the most common you will use at the range and misc shooting.
Define long range... to many people long range is 100yds. Long range to me is anything over 500 yds. Although the right setup in 223/5.56 will go out to around 1000yds, that isn't something the average shooter is going to be doing.
Depends on where your at at my home in WA long range is 50 yards but if your out on a ranch in Wyoming long range could be 1 mile or more its all subjective. AR-15/ m16 type rifles tend to be effective for about 900 meters or so, with the carbines you get less. However competitive ARs with the 1 in 7 twist barrels can load 72-80 grain bullets that get a little better accuracy. And most m4gerys now have the option of the 1in 7 twist to help out the shorter barrel.
If you want to shoot longer ranges(200+yards) a 20-24" barrel with 1/7 or 1/8 twist and 68-75 gr. bullets is your best bet. Of course any ammo with these heavier bullets will be more expensive as it is less common than the 55-62 gr. varieties.
My lyman manual shows an 80 gr boattail hollowpoint load for .223, and I've heard of some homebrewers going heavier than that, but you probably won't get a load like that to fit in a AR chamber. The 77 gr you have to load one at a time in the AR anyway. The best accuaracy you'll get from an AR is with a 55-62 gr bullet in the 1n9 twist 62-75grn with the faster twist. And That is a nice AR Draeger I take it you are a classIII or an Leo?