Or atleast make the first (and possibly ony) ammo die an d3.
This would also add insane amounts of malfunctions (or opportunities thereof).
And this seems to be precisely the problem here: combining several phenomena into a single die which is then rolled possibly multiple times (aka "ammo dice"). This way, ammo dice handle
- ammo usage and
- probability to hit.
Those are not directly linked however in a weapon, at least not how I understand and experienced guns, pistols etc.
Malfunctions occur in various parts of weapons, but they differ by weapon designs and by the source of the problem. A revolver will never suffer a "failure to feed" because the cartridge will always be in correct position. Unless of course, the revolver suffers a serious mechanical breakdown. Failures to feed can be a design problem or one of wear and team in the feed system.
Duds however will simply not fire in regular service rifles and they have nothing to do with the weapon. You clear them out and the weapon is exactly as good as before. Duds are a problem of the ammunition production, unless you suffer from a rare case of "your firing pin is to short to reach the primer of this particular type of ammunition", which happens, but is either an issue of ammunition production or you have a gun that was designed oddly. These cases are rare and wear and tear should not be an issue here, unless yo DIYed a new firing pin and cut it to short.
Which brings me to the next point. Many of these failures actually base on errors in work that you did before the fight: loading ammunition incorrectly, not servicing your weapon properly or using replacement parts that do not follow the proper specifications. And as such, these matters are specified not in the ammo dice, but in the reliability code of a weapon. Any by the way, if weapons in T2K are supposed to be no factory new - I am certainly all for it! - then we need a different set of reliability figures for "factory new" issues. After all, those will exist as soon a gun smiths open up shop and their weapons will degrade by use. Plus, their might be some old stashes to be found. Europe was full of weapons depots after all.
Of course shooting more means generating more opportunities for the combined reliability of ammo and guns to produce problems. So, ammo dice should not factor into reliability, but ammo might of course reduce reliability. That would mean malfunctions should be depending more on the shooter's skills and the gun-ammo combination than the shots fired. The shooter's skills will actually have preordained some of these problems way before the firefight, but for simplicity's sake, we should not start rolling out servicing of weapons, hand-loading ammunition and installing repairparts all the time. This is all only interesting, if something goes wrong in a fight.
So, ammo dice should not logically be part of the "malfunction process" at all. This is a matter of skill, either before the battle or during. But ammo dice could still determine usage of ammunition, right?
Well, yes, in a way. As (ex-)servicemembers know, ammo is used in a firefight like there's no tomorrow. Since, if you do not overpower your enemy, there won't be. So in modern combat, usage is pretty high. But for T2K this might not be true. With hunting and foraging being a big issue in a game of survival, ammo will be used sparingly. And firefights might become much shorter. A bolt-action rifle or pump-gun will not be used for "spray-and-pray", but only for shots that look "safe". It's no use to buzz the enemy with all you got, if you will not have anything left after that. What about the next guy then?
So, we need mechanic for cautious and "ammo saving" shooters. The single shot mechanic is one thing: Aim carefully, use one shot and hope you hit.
But well skilled individuals can also use a higher ROF and still not go "all nine yards" on the enemy. Maybe we should be able to use ROF-dice of the same type as our skill dice? Shooters with a dice type of d10 or d12 might gamble for two successes when really opening up on someone at only ROF1 with their gun, whereas a less skilled individual would have to use a ROF2 weapon for even the slightest chance of two additional successes, and possibly still using up 10 shots for no additional successes. A highly skilled soldier using a ROF4 machinegun could of course build up an additional 8 successes with these rules, but the chances are extremely low (who comes up with four 10+ on 4 d10 or d12?). And on their way to such an "ultra-kill" they would also use up 40-48 of these precious rounds of brass.