Hey, no problem.
After some observation, I found that the Vulcan meter actually rises as you shoot down enemy bullets, not as you kill enemies. That means that not only do you have reasonable control over the Vulcan meter, but you can get it more often than Nightcom did. Also, now I think the route Nightcom used actually is the fastest.
I figure that if you play your cards right, you can get the Vulcan Gun at the following points:
The boss of the first scene in Desolation Canyon (or whatever it's called).
Possibly the first boss of Ammunition Depot. You can use the gun to the right to charge up, as well as the boss. If you can't get it charged, you can always charge it up for the one below.
The Blue Orb boss. It fires bullets at you, so you can hit the bullets and hit the boss at the same time.
The scorpion-like boss. It also fires many bullets that you can use to charge up your meter.
Right before the last part of the armored train (the red part). If you're fast enough, you might even be able to use it against the jetpack guy, too.
Probably not possible, but the twin robots at the beginning of the final stage fire 3 bullets from each arm. 12 bullets at a time might allow you to get the Vulcan Gun fast enough to smoke them.
Either the boss right before the final boss, or the final boss. Most likely the former though, since it fires bullets like there's no tomorrow.
To accomplish this, you would have to leave some bullet-crazy enemies alive so you can use them to charge up. Here would be some good examples:
The very first boss, although you might not need to.
The first boss at Desolation Canyon.
The gun at the right on the first scene of Ammunition Depot.
The first boss of Ammunition Depot.
The blimps at the first scene of the stage where miners ride up in carts and throw dynamite at you.
The second boss of Ammunition Depot. Instead of using a bomb like Nightcom does, get the Grenade Launcher and blast the main part until the two arms fire, then you can charge up with them.
The scorpion-like boss.
The Gatling guns on the right on Armored Train.
The twin robots at the final stage.
The guys in the second scene who run up and fire a bunch of bullets down a narrow column.
The boss before the final boss.
Oh, and one more thing. Save the bombs for the blue-shirted guys only. The one in the first stage requires one, the next one two, and the last one two. I don't remember how many bombs you can get in the game, but that should cover them as long as you don't use them on anything else.
Wow, that's a long post. Sorry about that. I just hope you find it helpful.
