Okay its just a guess of me...
And it is based on the frequency and regularity of Delta C01243 Error happened to "ME" since 1.5 Update.

First of all I have 4 characters all different gearsets.
Number 1 has 4 Alphabridge and 2 Sentinel. Armed with M700 Carbon and 1 Wave M1A

Number 2 which is the Trouble maker in my account...I call it the Delta Producer.
It has 4 D3-FNC and 2 Tactician. Armed with MP5N and ACR-E and Special Rhino.

Number 3 is with 4 Striker and 2 Predetor. Armed with ACR-E and M44

Number 4 is 4 Lone star and 2 Reclaimer. Armed with Saiga 12 S and M60.

Also all other gearsets are with in their inventory.
Ihave tried to figure out why and played every day with different gears on each character their daily or weekly missions.

Number 1,3,4 Plays it without an Error. They just don't make any Errors. Never happened(since 1.5)

Unfortunately Number 2....I have tired the character with 4 Firecrest 2 Tactician. Worked fine. no Deltas....
As soon as I equip D3-FNC....Nightmare Begins...

Underground is Ok....no Delta when I am there with D3 FNC
In Normal field....partially ok
Some destricts like Gramercy....got Delta like every 5 steps. I just wanted to gather some HVT Points...
In Dungeon or what ever you might call...
especially those...with Blue Icons...is showing me the hell.
3 steps Delta load 3 Steps Delta...
Like Queens Tunnel or Lincoln Tunnel...Hate those two....
And when playing solo the Hard Mission...its so so....some lag and not that often Delta...
but when People join into the Party...Delta joins too
Challenging Mission. I just give up my hope and try to follow wehn I get back in.

So what I have thought....is that D3 FNC...is some Kind of bugged or what.
Because it is first time that People could use SMG with Shield and it Kind of created a collision with existing Code, that only allowed pistols.
I am no Progammer so I have no Idea.....but it smells....