I would personally have to call it for Roland, myself.
His aim and reflexes are well beyond superhuman, and his revolvers suffer no accuracy problems whatsoever, due to all craftsdwarfship being of the highest quality.
I've only read the first few Dark Tower books so far, but in the first one, the man in black more or less gets an entire town to go crazy and start trying to kill Roland at once. Roland was out in the street at the time and just started shooting all around himself without even really looking. Killed everyone in that town, never missed a single shot, I believe they were all one-hit headshot kills as well. Reloading wasn't an issue, he's just that fast. It's his life.
I'm pretty certain that if he sees Static before Static sees him, which from what's already been said is definitely the case due to not being a sparking electrical crazyguy flying around loudly, he is going to shoot Static, likely many shots in rapid succession, all of them guaranteed to be lethal if they hit. I don't care if Static is flying or moving at the time, Roland's aim is absolutely supernatural and trivialities like a moving target are not an issue. If Static's reflexes are quicker than a bullet, he may be able to deflect the bullets and save himself, but from what I've seen/read of Static his reflexes are probably just a bit quicker than a normal guy.
Feel free to tear my analysis up all you want, but there's my piece defending Roland. And how much electromagnetic force does it take to stop a bullet before impact, anyway? I'm kinda curious about that actually.
Roland wins due to, pretty much, stealth and surprise alone. Age and experience notwithstanding.
If this was a match against Magneto, however, I'd probably call it for Magneto.