Is combo duration capped at 15 sec

[mocoloco1]

              I'm asking this I have a melee weapon configured that gives me 15 sec of combo duration on its own.  When I equip Ash's augment Rising Storm, which has a passive of +10 sec combo duration, the stats of the melee weapon show that I should have 25 sec of in white, but that I'm only getting 15 sec in red.  Is this a bug, intended, or am I missing something in how Ash's augment works?  Thanks in advance for any responses.

[Quarterdane]

Have you tried modding the weapon to have an even longer combo duration, to see if that changes anything?

[mocoloco1]

Good point.  I think I got it figured out.  I was able to get the weapon up to 21 sec, so there's obviously no cap.  When I added Ash's mod, I had 31 showing in white and the 21 showing red.  My guess is that the white number is just what I have with the mod that's not attached to the weapon and the red is what I'll have without it.  I'll have to try to time it to see if that's true.  Thanks for the input!