Most successful military projects

[The Minsky Moment]

I'm far from an expert on fighter jets, but some of the MiG series (17? 21?) seem to have successful production history and reasonable costs, even if they tended to get shot down from time to time by Israeli pilots.

[Maladict]

GPS

[Iormlund]

This might be more of a challenge. What military investments/programs paid off well beyond expectations? Again post WW2.

The B-52 was mentioned in the other thread, the A-10 might be another contender?

This one is a way in the future, but I'd nominate the autonomous car. While looking for ways to automate military logistics, the DARPA Challenge seems to have boosted the field significantly.

[Razgovory]

GPS

Good one.  The most successful military projects are ones that are not only useful to the military but become useful for civilian life.

[11B4V]

I'll see you the AK-47, and raise you the Lee-Enfield rifle.  First developed in the late 19th century, main British and commonwealth rifle in both world wars.  It was retired in Canada by the Canadian Rangers two years ago.  Copies are still to this day being used in Afghanistan and Pakistan.

Post WW2?

Bah,
Pre WW2 the Mauser rifle. Lee Enfield was a much weaker action.

WW2 the M1 garand.

Post WW2 the AK 47

[grumbler]

F-4 Phantom.

F-16 falcon (still on production 47 years after the first one flew).

The K-Bar knife was late WW2, but still in production for the US military.

The Arleigh Burke class destroyers seem to have been very successful, still in production 39 years after the first ship entered service (maybe a record for a warship class).

The Nimitz Class carriers were in production for 41 years.

The Romeo class submarine still has two dozen or examples still in service 63 years after the first tasted salt water, outliving not only its successor, but it's successor's successor.

The Israeli Merkava tank is still in production 41 years after first seeing service (probably a record for a tank).

NAVSTAR/GPS is the big one, though.

[Barrister]

I'll see you the AK-47, and raise you the Lee-Enfield rifle.  First developed in the late 19th century, main British and commonwealth rifle in both world wars.  It was retired in Canada by the Canadian Rangers two years ago.  Copies are still to this day being used in Afghanistan and Pakistan.

Post WW2?

Bah,
Pre WW2 the Mauser rifle. Lee Enfield was a much weaker action.

WW2 the M1 garand.

Post WW2 the AK 47

But that's just it - the Lee-Enfield spanned all three periods.  That kind of longevity counts for something.

(and I know the risks of debating military arms with an ex-army soldier, but I'm going to chance it anyways)

[11B4V]

I'll see you the AK-47, and raise you the Lee-Enfield rifle.  First developed in the late 19th century, main British and commonwealth rifle in both world wars.  It was retired in Canada by the Canadian Rangers two years ago.  Copies are still to this day being used in Afghanistan and Pakistan.

Post WW2?

Bah,
Pre WW2 the Mauser rifle. Lee Enfield was a much weaker action.

WW2 the M1 garand.

Post WW2 the AK 47

But that's just it - the Lee-Enfield spanned all three periods.  That kind of longevity counts for something.

(and I know the risks of debating military arms with an ex-army soldier, but I'm going to chance it anyways)

I can see your point but the Mauser spanned just as long. Major innovations, stripper clip loading and controlled round feed. The Enfield was a good rifle to be sure, but not the success the Mauser was and is.

There is a reason the mauser action way outstripped the Enfield in the civilian sector too. It is still copied and also made by Mauser to this day and the Enfield isn't.

M24 series
vz. 24/vz. 33
Type 24 rifle
M1903 Springfield
Pattern 1914 Enfield
M1917 Enfield
Arisaka Type 38/Type 99
M48 Mauser
Kb wz. 98a/Karabinek wz. 1929
FR8

Modern hunting/sporting rifles like the Parker Hale, Holland and Holland, CZ 550, Heym Express Magnum, Winchester Model 70, Mauser M 98, etc. Modern sniper rifles like the GOL Sniper Magnum and Zastava M07. Versions of the Mauser action designed prior to the Gewehr 98's introduction, such as that of the Spanish/Swedish Mauser rifles and carbines, lack the third locking lug and feature a "cock on closing". It was the most copied bolt action rifle.

There's a reason why the British and American got the snot shot out of them in the Boer War and Spanish American War respectively. Their opponents were using Mausers.

[11B4V]

AK-47 and successors for enduring popularity maybe. Origin is arguably WWII though. 

Yes the German StG 44 and M1 Garand. Here's a good article.

https://www.thefirearmblog.com/blog/2015/05/05/rifle-paternity-test-pinning-down-the-m1-garands-influence-on-the-ak/

The M1 Garand definitely laid ground for today's generation of automatic and semi-automatic weapons.

[11B4V]

F-4 Phantom.

F-16 falcon (still on production 47 years after the first one flew).

The K-Bar knife was late WW2, but still in production for the US military.

The Arleigh Burke class destroyers seem to have been very successful, still in production 39 years after the first ship entered service (maybe a record for a warship class).

The Nimitz Class carriers were in production for 41 years.

The Romeo class submarine still has two dozen or examples still in service 63 years after the first tasted salt water, outliving not only its successor, but it's successor's successor.

The Israeli Merkava tank is still in production 41 years after first seeing service (probably a record for a tank).

NAVSTAR/GPS is the big one, though.

Nah, I'd argue the T-72

[Valmy]

11B4V, what do you think of the Mannlicher compared to the Mauser?

[The Brain]

The Carl Gustaf recoilless rifle is still in production, after 70+ years.

[Maladict]

Nah, I'd argue the T-72

Wow, they're still making them?

[11B4V]

Nah, I'd argue the T-72

Wow, they're still making them?

Don't know. I'd argue the T72 is far more successful than the Merkava

[The Brain]

I'm not sure exactly what the expectations were in each case, but for several countries that developed nuclear weapons after WW2 those weapons have certainly been very successful (they may also have been expensive, but the rewards are also great). Just after WW2 it wasn't clear that the family of nuclear states would remain so small, but since it is having nuclear weapons pretty much guarantees Significant Power status.