ok read this now, before you start thinking about things i havent been talking about. I am talking about expected results vs actual, the discrepancy representing a bug. I am not commenting on whether gear takes more or less XP than year 1(it is easier to level gears in year 2, no question), or is easier or harder to level up. This is purely about expected vs actual.
I took TWO blue MG heavy weapons. Level 40, 265 and 267 light respectively. No telemetries, no class item to boost XP on MGs.
Starting with the 265 MG
I used 6 motes of light = 6000xp
The result: all upgrades unlocked.
Conclusion: 6000xp is enough to unlock all upgrades on a level 40 blue 265 heavy machine gun
Second test:
267 light
Turned in two bounties, for 3000xp each, for a total of 6000xp. This is the same expected XP as provided by 6 motes of light.
Graphically - barrel option 2 is unlocked, and the first perk bubble is filled in just past the 50% mark.
Per API - 180/1224 towards unlocking perk 1.
To test the reliability of the API, i then used a single mote of light. The API subsequently reported 1180/1224, a gain of 1000 as expected. Respectively, the graphical UI now shows the perk 1 nearly unlocked, filled in to between 11 and 12 oclock.
No + icon appeared after using the single mote of light, so it is probable that no phantom unlocks occurred, and that the API numbers are accurate for this test.
As a third test, i used a level 40 264 light MG again.
API shows 1020 XP to first unlock.
i used a single mote of light.
Graphically: barrel option 2 is showing between 11 and 12 oclock. Perk 1 and barrel option 3 are at ~5 oclock. No + icons have appeared, suggesting no phantom nodes unlocked.
Per API: 1000/1020 towards next unlock. This is consistent with the graphical UI, and falls within expectations.
Summary:
it requires 6 motes of light to completely unlock a level 40 blue heavy weapon with light in the 260s.
6 motes of light is thought to equal 6000 XP, or 1MoL = 1000 xp.
6000xp worth of bounties did not completely unlock a level 40 blue heavy weapon with light in the 260s.
Non-statistically significant testing suggests that