No write up from me here, Bungie pretty much says everything needed to be said. Source

ASSAULT RIFLE

A certified stalwart in the UNSC’s arsenal, the Assault Rifle has scrubbed more than its fair share of Covenant scum up close and personal. First introduced with Halo: Combat Evolved, it missed a beat in Halo 2, but made its triumphant return to Halo 3 and by now you should know it’s making a return with a pretty significant visual overhaul in Halo: Reach, as seen in yesterday’s 3D art asset comparisons.

It’s not the only weapon that’s being upgraded, according to Josh, one of Halo: Reach’s sandbox designers.

“Everything has been touched in one way or another. That being said, some of the weapons had already gone through some serious iterations at this point in Halo’s life and so in some cases changes have been kept to a minimum. Either way, the visual face lift was worth its weight in gold. All the weapons, including the classics, are looking AMAZING!”

Sage, the project’s lead sandbox designer, briefly expounds on some of the subtle changes being made to the series’ staples:

“Returning weapons will, for the most part, maintain their classic roles and generally feel the same. If you’re playing at the pro level, you can expect to notice minor changes to every weapon.”

Of course, there’s some new stuff in the mix as well.

Designated Marksman Rifle

“The DMR, or Designated Marksman Rifle,” Sage notes, “is a medium-to-long range support weapon. In range and play style it fits between the Assault Rifle and Sniper Rifle in the Human sandbox. Powerful in skilled hands, its rewards the ‘gunfighter’ – the calm, accurate player, who like to be in the fight. Its primary role is to suppress snipers and soften opposition before the shock troops close.”

When you do find yourself in the fight, shock troops rushing your position, Josh has some slightly less merciful tips to help keep you alive when you have the DMR in your hot little hands.

“The DMR is deadly accurate if you breathe through the shots and get into the rhythm of firing it, but it quickly falls apart if you freak out and really start slamming the trigger. A player with surgeon’s hands will be able to use it anywhere, anytime. Players that struggle with their composure in a heated fight however will find it better suited to working guys from a distance, picking off the sick and weak from the herd.”

And for those looking for that elegant weapon for a more civilized age, it looks like the DMR might be the implement of war you’re looking for.

“Personally, I’ve found that I always like to have a DMR in my back pocket in the way that I would have kept around the pistol in Halo: Combat Evolved,” Josh says. “Either way, the big news with the DMR is that it’s particularly good at shooting Covenant in the face.”

Needle Rifle

Speaking of Covenant forces, Reach may be a UNSC military stronghold, but the Covenant war machine is at the height of its military power. The Needle Rifle is one of the more fearsome and unique weapons in their invasion force’s arsenal and a fitting counter to the Designated Marksman Rifle. It’s also one of the weapons we’ve revealed that seems to be surrounded with the most ambiguity. Let’s clear some stuff up.

“The Needle Rifle is one of my personal favorites,” Josh notes. “While it is very similar to the Carbine in several ways, including its ability to headshot (Unicorn!), it’s still 100% Needler and comes stock with the ability to super-combine when it comes in contact with your enemies and spread them like jam across a warm piece of toast. Unlike the Needler, the rounds don’t track your target…because that would just be ridiculous.”

Sage offers up his own additional details.

“The Needle Rifle is the Covenant’s answer to the DMR. It’s a medium-to-long range weapon with powerful anti-shield damage. It’s faster and more accurate than the DMR, but doesn’t have the same stopping power. It’s a Blamite! super-combining weapon (three shots to an unshielded body) that can also score headshots.”

By Design

It should be noted here that all of these details are subject to change. Sage, Josh, and the rest of the team continue to put this trio of weapons, along with all of the other sandbox toys to the test time and time again, ensuring that the end product delivered in the fall will be as fair as it is fun. Seems it’s even become a mantra with Josh. How do they make sure everything is tuned just right?

“Testing! Testing! Testing!”

But it ain’t all about the aftermath. Sage and Josh are on their toes anticipating where new systems like Armor Abilities could turn delightful multiplayer fun into an exploitable and unfair set of game busting superpowers.

“We’ve built the systems with some minor drawbacks that are there to make sure you’re not a God… an invisible, sneaky, evil God to be exact.”

“Balancing a game is not an exact science,” Sage adds, “because we don’t always want total equality. Some weapons and abilities are intentionally designed to be more or less powerful. That said the best way to balance a game after looking over the raw numbers is to play test it as much as possible. Sometimes we also reduce the number of variables and run specific tests to see if the results fall within our desired outcome. Like DMR vs. Needle Rifle tests.”