Decline order?
 

In the mission screen, there should be an option to decline it due to damage, or low ammo; then mission should change to return to base

In the last game, I have done like 4 missions in a row, and I simply don't have enough torpedoes to keep going

Over-Spec in my opinion, not pursuing the mission is effectively rejecting it, and it's an option available to the player, so I don't see the extra value in adding a UI option. Moreover, it's the Navy, you don't disobey orders. It would be an immersion killer to add such an option to a military based game.

Be more aggressive commander!

You still get the lost mission, unfairly

It is either that or maybe the game check weapon stores and damage, and orders RTB if you are damaged or your stores are at or below 20%

Sure, lets fit a ram in the bow and I will gladly keep fighting once I run out of torpedoes

Unfair would be to force the Soviets to halt their war effort while you go and reload your stores. You have to accept that you may not be able to complete every mission. Cold Waters assumes so: it only pushes you one victory away from the campaign's conclusion.

Now, the game does check and give you resupply missions accordingly (at least when you run low on ordnance), so if you haven't received those orders yet, you still have enough weapons to accomplish at least one more mission.

I still had torpedoes, but only Mk16s; and the mission was ASW

I guess I will need to remember to shoot them all next time so I get a replenish mission

How many missions you can fail and still win the game?

Ah, right. I can fix that, I think.

There's your problem, you actually carry Mark-16's. :03:

If you maintain an even win/lose ratio, the war at sea can go on until the land war concludes, one way or another. Which can take a pretty long while with the current general event intervals (perhaps too long?). Well, actually, given tonnage sunk counts towards your side's victory points, breaking even on missions would still have you creeping towards a positive conclusion.

Not sure just how the land war intervenes. If either side achieves land dominance, does the final (SSBN) mission trigger or does the conflict as a whole simply end?

Not need.
Orders do not discuss.

Only Situation to rtb and not trying to fulfill the orders in my eys is an badly damages Sub.
In this case, an "rtb order " should be implemented.

E.g. with hull lower than 50% and 2 sections with flooding.
or having an destroyed sonar or something like this.

Wastel

every time I get not enough ammo to fill all tubes or some damage, I get the recall mission

not an issue for me - if you have ammo to fill the tubes, the missions keep coming...if not, admiral says come home to stock up

I have found when going for tonnage records that tonnage triggers the SSBN mission prematurely, where the land war is not concluded...but all of a sudden I get the "peace talks" message, and then shortly after the SSBN hunt - even though I have barely completed any missions at all

The Maskirovka strikes again