Editing M512 smooth-bore high-velocity cannon

{{Era|UNSC|HCW|Post}}
{{Weapon Infobox
|image=[[File:HVC.png|300px]]
|manufacturer=
|series=
|type=Vehicle-mounted cannon
|cost=
|variant=
|service=[[Human-Covenant War]] <br> [[Post-Covenant War conflicts]]
|affiliation=[[United Nations Space Command|UNSC]]
|weight=
|length=
|ammotype=
* "Tungsten" round<ref name="tungsten"/>
*[[S1 canister shell]]
|feed=Unlimited 
|operation=
|rate=15 rounds per minute.<ref group="note">The 15 rounds per minute rate of fire is based off a calculation of 1 round fired every 4 seconds, 15 rounds fired every 4 seconds would come out to 60 seconds. <math>15 x 4 = 60</math>. This is based off of the reload time of the 90mm cannon in ''Halo 3''.</ref>
|velocity=
|range=Long
}}
{{Quote|Hey, how does 90 millimeters of tungsten strike you?|[[Gunnery Sergeant]] [[Stacker]] remark of the M512 smooth-bore high-velocity cannon during [[Battle of Installation 00]]<ref name="boom">'''Halo 3''', campaign level ''[[The Ark (level)|The Ark]]''</ref>}}

The '''M512 smooth-bore high-velocity cannon''', or simply the '''M512 cannon''', is a 90mm gun mounted on [[M808 Scorpion]] tanks. 

==Design details==
The M512 cannon is stated to have a smooth-bore high-velocity construction.<ref>[[Halo: The Essential Visual Guide]], page 164</ref> Smooth-bore indicates that the barrel of the gun lacks rifling, and high-velocity indicates that the cannon is engineered for the firing of ammunition with a notably high muzzle velocity. The cannon is typically mounted in the un-manned turret of an M808-series Scorpion tank and fed via autoloader. 

===Ammunition===
The M512 cannon is compatible with at least two varieties of ammunition. The first is a projectile which includes tungsten in its construction, and was utilised by [[Marine]] [[M808C Scorpion|M808C]] tank units attached to the ''[[Forward Unto Dawn]]'' during the [[Battle of the Ark]].<ref name="tungsten">'''[[Halo 3]]''', campaign level ''[[The Ark (level)|The Ark]]''</ref> The second type of ammunition employed is the [[S1 canister shell]], which provides the Scorpion tank with a powerful method of engaging large numbers of lightly-armoured targets, being especially lethal against infantry <ref>'''[[Halo Wars: Official Strategy Guide]]''', ''page 42''</ref>

==Gameplay==
===Advantages===
The M512 cannon can effectively destroy most light vehicles with only one shot. Even heavy vehicles like the Covenant [[Type-26 Wraith]] can only withstand two to three rounds before being destroyed. Because of its high area-of-effect and high velocity it is a very useful anti infantry weapon as well, able to kill even the toughest infantry like the [[Mgalekgolo]] in just one shot. Shots from a 90mm Cannon are also very effective at destroying walls or structures if enough shots are fired at it. The cannon also has very little recoil, which may be attributed to an added muzzle brake or its design.

===Disadvantages===
The M512 cannon is unable to fire on anything too close to the cannon or the Scorpion's chassis, as the cannon cannot traverse that close. The cannon's high area-of-effect means that precision kills are next to impossible - friendly infantry or vehicles near the target are likely to feel the force of the blast as much as the intended target. The M512 cannon must be reloaded after every shot and takes between three and four seconds, which may give the enemy enough time to react against the tank. In addition, the smoke trail the round leaves behind when fired can compromise the tank's location, making it easier for enemies with anti-armor weaponry to locate the Scorpion in multiplayer.

==Tactics==
===Campaign=== 
*In ''[[Halo: Combat Evolved]]'', the cannon is quite inaccurate; the shot had high deviation, but compensated with a large explosive radius.
*Using the M512 in the level [[Delta Halo (level)|Delta Halo]] in ''[[Halo 2]]'' is tricky, particularly when the player moves into tight quarters and encounters [[Type-32 Ghost]]s due to the steep angles of the Forerunner structures. Self-harm is a constant worry. It is best for players to remain in an open spot and let the Ghosts come to the player, picking them as soon as they appear. If this option is not available it is recommended that players use the [[M247T machine gun|Scorpion's turret machine gun]] instead, which is just as effective thanks to its impressive accuracy and high damage.
*If the player acquires a Scorpion near the beginning of [[Quarantine Zone (level)|Quarantine Zone]], the rest of the mission becomes spectacularly easy; the range of the M512 allows the user to pulverize any and all Flood resistance in their way, and two-shot Sentinel Enforcers with ease. 
*The M512 is undoubtedly at its best in ''Halo 3''; its accuracy is near pin-point with almost no drop, and the splash damage is predictable enough to allow for a skilled tank gunner to eliminate entire Covenant squads with a single round. This is most visible during the latter part of ''[[The Ark (level)|The Ark]]'', where engagements with enemies take place across wide open areas
*In ''Halo 3'' on the level The Ark, Phantoms can be brought down with a few well placed shots at one of their engines.

===Multiplayer===
*In ''[[Halo 3]]'', the 90mm cannon requires players to lead their shot against moving targets. Move the reticule just slightly ahead of the target and fire. When going up against aircraft like the [[AV-14 Hornet]] or the [[Type-26 Banshee]], players must also aim ahead of their target as well as above to ensure a direct strike. Depending on how fast the target is moving, the reticule needs to be slightly ahead of the target or just outside the reticule.
*In ''[[Halo: Reach]]'', most maps that spawn a Scorpion have large, open lines of sight; perfect for the cannon's accuracy. Sit in relative safety and pick off targets of opportunity.
*In ''[[Halo 4]]'', the cannon's shots produces a noticeable vapor trail similar to that of a sniper rifle when fired, and reveals the tank's location. The cannon's shells travel much slower than they did in ''Halo: Reach'', and arc at a higher rate than before. Also, unlike previous ''Halo'' titles, the tank round can be bounced off some surfaces.

==Trivia==
* If the cannon is [[Modding|modded]] onto another vehicle, such as a [[M12 Warthog|Warthog]] or a [[AV-14 Hornet|Hornet]], the weapon's recoil will be so powerful that the smaller vehicle will go flying.<ref>[http://www.youtube.com/watch?v=ojl07pQt4tw '''YouTube.com''', ''Halo: Reach .MAP Mod - TankHog'']</ref><ref>[http://www.youtube.com/watch?v=KMkmleqJ8oc '''YouTube.com''', ''halo 3 hell hornet and scarab banshee mod'']</ref>
* "High-velocity" is a real-world term for a tank cannon with a projectile velocity between 1,550 and 3,350 feet per second (472 m/s to 1,021 m/s), such as the 90mm M3 Gun used by the M26 Pershing.<ref>[http://fas.org/irp/doddir/army/ar310-25.pdf "Dictionary of United States Army terms"]</ref>
* In ''[[Halo: Reach]]'', it is possible to shoot off the cannon of the Scorpion using another Scorpion.

==Gallery==
<gallery>
File:90mmHVC.jpg|A study of the M512 Smooth Bore High Velocity Cannon.
File:H3 Scorpion firing at a Scarab.jpg|An M808 MBT firing its M512 SBHV at a Scarab.
File:Tank round.jpg|A 90mm shell casing.
File:M512_expended_shell-_Scorpion.jpg|An expended shell casing rolling down the back of a Scorpion after being ejected.
File:HR-90mmShell.png|A spent 90mm shell in ''Halo: Reach''.
File:H4-M512-SBHVC-TankShell.png|A spent 90mm shell in ''Halo 4''.
</gallery>

==Notes== 
<references group="note"/>

==List of Appearances==
*''[[Halo: The Fall of Reach]]'' {{1st}}
*''[[Halo: Combat Evolved]]''
*''[[Halo 2]]''
*''[[Halo 3]]''
*''[[Halo Wars]]''
*''[[Halo 3: ODST]]''
*''[[Halo: Reach]]''
*''[[Halo: Combat Evolved Anniversary]]''
*''[[Halo 4]]''
**''[[Spartan Ops]]''
*''[[Halo: Spartan Assault]]''
*''[[Halo: Escalation]]''
*''[[Halo 2: Anniversary]]''
*''[[Halo: Spartan Strike]]''
*''[[Halo: Ground Command]]''

==Sources==
<references/>

{{UNSC heavy weapons}}
[[Category:UNSC ground weapons]]
[[Category:Projectile weapons]]