5 inch/38 Mk.12 (127 mm)

Description

The 5"/38 Mk.12 is a dual-purpose 127 mm cannon, developed and used prolifically on American vessels since its introduction in 1934.

General info

The 5"/38 is notable for having the highest fire rate of any WWII-era 127 mm gun out of any nation in the game. This stellar rate of fire results in a very high damage output, placing ships equipped with the 5"/38 very high with regards to gun firepower. The destructive capabilities of the shells are also quite high, with competitive penetration and explosive filler. The only limitations on the use of the 5"/38 are the relatively poor ballistics and accuracy at range, which are partially compensated for by the high fire rate of the cannon.

Available ammunition

Not all ammunition listed is available on all vehicles equipped with this weapon.

Penetration statistics
Ammunition	Type of warhead	Penetration @ 0° Angle of Attack (mm)
		1,000 m	2,500 m	5,000 m	7,500 m	10,000 m	15,000 m
AAC Mk.34	HE	36	36	36	36	36	36
Common Mk.32	Common	124	103	77	58	46	37
SP Common Mk.46	SP Common	150	125	93	71	56	45
AAVT Mk.31	HE-VT	36	36	36	36	36	36

Shell details
Ammunition	Type of warhead	Velocity (m/s)	Projectile mass (kg)	Fuse delay (s)	Fuse sensitivity (mm)	Explosive mass (TNT equivalent) (g)	Ricochet
							0%	50%	100%
AAC Mk.34	HE	792	25	0	0.1	3,220	79°	80°	81°
Common Mk.32	Common	792	24.49	0.01	6	1,150	47°	60°	65°
SP Common Mk.46	SP Common	792	25	0.01	6	906.5	48°	63°	71°

Proximity-fused shell details
Ammunition	Type of warhead	Velocity (m/s)	Projectile mass (kg)	Fuse delay (s)	Fuse sensitivity (mm)	Arming distance (m)	Trigger radius (m)	Explosive mass (TNT equivalent) (g)	Ricochet
									0%	50%	100%
AAVT Mk.31	HE-VT	792	25	0	0.1	457	23	3,220	79°	80°	81°

Comparison with analogues

Give a comparative description of cannons/machine guns that have firepower equal to this weapon.

Usage in battles

Playing with US destroyers, the 5 inch/38 Mk.12 will be your main cannon up until you reach cruisers. Playing as Cruisers, this cannon will make up your secondary armament, fending off planes or other naval vessels that are weaker than you. Your main shell to use against other naval targets is Common Mk.32, or SP Common Mk.46, as they are SAPCBC (Semi-Armour Piercing), and offer the the best between both penetration and damage. HE-VT can be taken as well, and will be effective against air targets, or other naval vessels as the shell is proximity-fused. With the reload rate varying from 4.0 seconds to 2.0, the gun can easily make work of knocking out opponents within minutes.

Against Destroyers: SAPCBC can disable/sink other destroyers within a few seconds to a few minutes, depending on the range and lead of your target. While lacking in explosive mass than some other similar cannons your reload rate makes up for it. At closer range, it is best to target turret components such as ammo elevators, or ammunition stowage to disable/reduce the enemy's firepower against you, and eventually aiming for the hull of the ship, such as the engine deck and transmission area while taking advantage of taking your fire rate.

Against Cruisers: The 5 inch Mk.38 starts to fall here once you start facing Light and Heavy Cruisers. The SAPCBC shells lack in explosive power, with damage output being subpar. Playing as a destroyer, your best option to to aim for the turrets of Light and other possible Heavy Cruisers in hoping of disabling their turrets, although vessels such as the USS Somers or USS Moffett can defeat other cruisers, it's best to stay in a support role. While HE may not be effective, there may be a chance on starting fires on enemy decks as well, throwing them off guard. Take use of your exceptional reload rate, and if possible have and provide support for other friendly vessels that have the firepower to take down cruisers. An possible exception is the USS Atlanta that houses eight 5 Inch/Mk.38 in dual turret mounts, as the Atlanta can fire up to 14 guns broadside, shelling enemy vessels before they can properly counter you. Despite the fall in damage and firepower against cruisers, the 5 Inch/Mk.38 is one of the best 127mm cannon out there that can go against cruisers.

Against Air Targets: HE-VT can make great work against other enemy aviation aircraft. With US Destroyers, it's best to find cover first if you can before you engage enemy air targets as you will be distracted and focused on the enemy aircraft. Leading may be difficult, but HE-VT will compensate for that if it flies into the path of the enemy air target. Have your AI Crew controlling your autocannons to assist you if aren't able to kill an aircraft that gets too close. With Cruisers, it's best to have AI take care of AA fire, as they can be deadly with their crew skills ranked up. Be aware the fuse won't activate within 500 m or so.

Pros and cons

Pros:

• Very good rate of fire
• Access to HE-VT shells
• Good firepower
• Good post-penetration damage

Cons:

• Bad accuracy at long range
• Subpar muzzle velocity

History

Examine the history of the creation and combat usage of the weapon in more detail than in the introduction. If the historical reference turns out to be too long, take it to a separate article, taking a link to the article about the weapon and adding a block "/History" (example: https://wiki.warthunder.com/(Weapon-name)/History) and add a link to it here using the main template. Be sure to reference text and sources by using <ref></ref>, as well as adding them at the end of the article with <references />.

Media

Excellent additions to the article would be video guides, screenshots from the game, and photos.

See also

Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:

• reference to the article about the variant of the cannon/machine gun;
• references to approximate analogues by other nations and research trees.

External links

• [Wikipedia] 5"/38 caliber gun

Japan naval cannons
20 mm	JM61 · Type 98
25 mm	25 mm/60 Type 96
37 mm	Type 4 · Type 11 pattern 1922
40 mm	40 mm/62 Vickers
57 mm	Type 97
75 mm	Type 88 AA
76 mm	3-inch/40 Type 41 · 8 cm/40 3rd Year Type · 8 cm/60 Type 98
100 mm	100/65 mm Type 98 mod A
120 mm	120 mm/45 3rd Year Type · 120 mm/45 10th year type
127 mm	5 inch/40 Type 89 · 127 mm/50 3rd Year Type
140 mm	140 mm/50 3rd Year Type
152 mm	6-inch/45 Type 41 · 15 cm/50 Type 41
155 mm	155 mm/60 3rd Year Type
200 mm	20 cm 3rd year type No.1
203 mm	20 cm/45 Type 41 · 20 cm/50 3rd year type No.2
356 mm	36 cm/45 Type 41
410 mm	410 mm/45 Type 3
	Foreign:
20 mm	20 mm/70 Oerlikon Mk.II (USA/Britain)
40 mm	Bofors L/60 Mark 1 (USA) · Bofors L/60 Mark 2 (USA) · Bofors L/60 Mark 3 (USA)
47 mm	3 pdr QF Hotchkiss (Britain)
76 mm	3-inch Mark 10 (USA) · 3 inch Mk.33 (USA) · 3-inch Mk.34 (USA)
120 mm	4,7-inch/40 Armstrong (Britain)
127 mm	5 inch/38 Mk.12 (USA)
305 mm	12-inch/45 Vickers (Britain) · 12-inch/50 Vickers (Britain)