M41 SPNKr

Were you also looking for the M19-B SAM Missile Launcher, mentioned in Halo: Ghosts of Onyx, or the M19 SSM Rocket Launcher, used in Halo: Combat Evolved and Halo 2?

The M41 SSR MAV/AW is a heavy ordnance weapon of the UNSC arsenal used in Halo 3. It is different from the M19 SSM Rocket Launcher used in Halo: Combat Evolved and Halo 2.

Design Details
The M41 SSR is a heavy ordnance weapon in the UNSC arsenal that fires a 102mm Shaped-Charge High-Explosive Surface to Surface Missile. The launcher sports a 2x scope and can fire rockets over long distances with devastating accuracy, although its altitude decreases over longer distances, this model is not to be confused with the M19 SSM Rocket Launcher. The M41 is, however, identical to the M19 variant rocket launcher. The M41 uses a unique design then any other rocket launchers. When reloaded, the barrels are removed, two preloaded barrels are then inserted back onto the unit. With this mechanism, a Marine can greatly reduce the weight he carries without throwing the weapon away like some contemporary disposable rocket launchers. This setup is very similar to that of the Javelin Anti-Tank System currently used by the U.S. military.

Advantages
The Rocket Launcher spreads a huge amount of damage over a large area. It is capable of taking out entire groups of infantry at any range and can kill both the passengers and crew of nearly any vehicle with the exception of the Scorpion Tank or Wraith which takes two to three hits with. For an anti-tank weapon it is capable of inflicting massive damage to tanks because of its ability to quickly launch two consecutive shots.

Disadvantages
Several things counterbalance the M41's sheer power the rocket, though powerful, is implemented in-game as an anti-vehicle weapon, not designed for engaging infantry. Thus its reload time is quite slow, as it takes about three to five seconds for the M41 to be fully reloaded. The rockets leave a trail of smoke in their wake, giving away the operator's position and necessitating a fire-and-displace strategy of engagement. Ammunition is often limited or unavailable, and the operator can carry only 6 extra rockets at once, for a total of 8 rounds. The speed of the rocket itself is slow. A skilled operator can be effective against a moving target at medium to long range. The biggest disadvantage to the operator is the blast range of a rocket; if fired too close the splash damage can severely injure or kill its operator if fired carelessly into surrounding terrain or at an enemy. An explosion near a rocket in flight will cause it to deflect. Deflected rockets tumble end over end, and will explode if they strike an object.

Influences
On the side of the M41 the labeling on the launcher and the rectangular cases that contain rocket ammunition has the words SPNKr. The M41 SSR is essentially a Halo Universe copy of the SPNKR-X17/18 SSM Launcher (Lazyboy) from the Marathon. The word "SPNKR" is a short abbreviation of the word Spanker and the line serves as an inside joke for both fans and Bungie of their former series.

Changes from M19 SSM Rocket Launcher
In Halo 2, the Rocket Launcher is much weaker than the one from Halo: Combat Evolved, although it still can destroy a small sized vehicle with one shot. Despite how many rockets it takes to take out a vehicle, the Halo 2 rocket launcher has a lock on system that tracks an enemy vehicle and nearly always hits its mark, destroying it.
 * The M41 HEAT rocket travels faster than its M19 counterpart.
 * The tubing is also a metallic silver color rather than a synthetic black.
 * No longer has the homing feature offered in the Halo 2's M19 model, and is more similar to Halo: Combat Evolved's Model.
 * Maximum ammo is 8, just like in Halo 2.
 * Different firing sound effect.
 * Faster reload.
 * Faster melee.
 * Ammunition indicated in scope when zoomed in.
 * HUD ammo indicator illustration changed.

Campaign

 * It is best to save the Rocket Launcher for the final encounter on The Storm (Level) as two shots will destroy the anti-air gun and finish the mission quickly. Combined with the Sniper Rifle found near the end (soon after witnessing a Longsword crash in the distance), one can easily end the level without engaging the large group of Covenant on the hill. Using the scope on the Sniper Rifle, one can zoom in on the AA gun's power core, line up a shot, then with proper timing, simply fore off two rockets and destroy the gun, ending the level quickly and (relatively) painlessly. The Chieftan will still be able to fire on you, though, so take caution when aiming.
 * Saving several rockets for the final encounter on The Ark (Level) can save you a lengthy encounter with the Brute Chieftain at the end; this is even more useful when engaging them on higher difficulties. These can be found by the downed Pelican just after the first Hunter encounter.

Multiplayer

 * When attacking a Banshee or Ghost with the rocket launcher, wait until the vehicle approaches. Get a slight lead on it before pulling the trigger. You don't need that much of a lead: about the size of the targeting reticule will suffice, depending on how far away the target is.
 * Be careful using the rocket launcher against infantry wielding a Gravity Hammer as the hammer can deflect the incoming rocket.

Trivia

 * The Rocket Launcher has a considerable recoil, although the very nature of its design requires it not to recoil. When the rocket is fired, the gases generated by its launch is shunted through the back of the barrel. When a rocket is fired in real life, the only sensation is an impulse and a forward shift in the weapon's center of gravity as the projectile leaves the weapon.
 * In Halo 3, it is possible to shoot down the rockets fired from this weapon with a Battle Rifle or a Covenant Carbine as well as a Sniper Rifle or a Particle Beam Rifle. This is probably possible with other head-shot enabled weapons. The SMG, however, will not work. This was tested thoroughly in Theater Mode. There is a slight delay between when the shot hits the rocket and when the rocket explodes, however, which should be taken into consideration.
 * Though it carries much less ammo, it is often preferred over the Fuel Rod Gun due to the rocket being stronger, faster, more accurate, possessing larger splash damage, and can't deflect off the terrain like the Fuel Rod Gun can.
 * A rocket fired from the Rocket Launcher will travel faster then any multiplayer vehicle at top speed. This was tested and proven by the Halo 3 Mythbusters using a Ghost.
 * It is impossible to hit yourself with your own rocket. If you shoot it at a receiver node and go through the sender node to catch up with it it will pass harmlessly through your body. This was tested and proven by the Halo 3 Mythbusters. This does not, however, make one immune to the splash damage.
 * On the last level of Halo 3: ODST there are four rocket launchers with 1000 rockets each for use in Vidmaster Challenge: Deja Vu (they only appear on Legendary, with the Iron Skull activated).
 * When ODSTs get their rocket launcher, they usually say "back blast" to warn others of the rocket's fiery plume.

Internal

 * M19-B SAM Missile Launcher
 * M19 SSM Rocket Launcher