Heavy Laser Canon, Marksmanship, and Critical Damage

[RebelPilot1978]

Heavy Laser Canon reads: "After the Modify Attack Dice step, change all critical damage results to regular damage results.

Marksmanship reads: While you perform an attack, if the defender is in your bullseye, you may change 1 regular damage result to a critical damage result.

Which occurs first? Does the canon cancel all critical damage, then marksmanship picks adds one back? Or is the order reversed?

[Kris M]

Marksmanship happens in step 2b of the attack (Modify Attack Dice). Heavy Laser Cannon happens after the Modify Attack Dice step.