When Dan realized the man flinched from bullets -- not totally bulletproof, are ya? -- he changed his tactics.
Keep him at a short distance and keep shooting. No need to retreat all-out. As long as Dan could keep hitting the bastard he could take advantage his flinch to evade a doubtless fatal strike. A lifetime of practice let him reload fast enough to keep it up.
Curtis had given Dan a basic tenant: Never stop attacking. Even when you retreat, attack. Dan followed it with absolute devotion.
He tried not to think about what would happen if he ran out of cartridges.