I've been farming heroic bounties for hours and I am never rewarded with a red border weapon. If bungie didn't want us to craft these weapons, why in the hell are they so hard to aquire? I've tried all farming methods, none of them are dropping red border weapons.
To be honest I stopped patrolling Neomuna pretty quick after the campaign. Just not fun slogging on around a patrol area that annoying… one shot threshers, red bar bullet sponges, and lackluster rewards.
I’m usually a completionist but I’m barely halfway on some of the the terminal overide things and only unlocked one red border.