In this past, you will have two weapons: the Colt 1851 and the Sticky Crossbow. The Colt fires a burst of two bullets, and the Sticky Crossbow has a six bolt clip, but the bolts only explode on reloads.
There are two enemies here: Dr. Wolfenclaw and his monster. Wolfenclaw will buff his monster if you leave him be, so take a potshot with the Colt when possible. He will run away with an invincibility shield, but eventually drop it. Four hits will kill him.
The monster is the real boss. He has four attacks. The first is a random spray of bullets. The second is forming a bullet sword and swinging it around, so keep your distance. The third is lightning bullets that will come from the top of the screen. The fourth creates an emblem design, that will expand outwards, but if you're standing far enough away, you can easily slip through the holes.