Specifically the modified and full choke mods have descriptions which call out that they are not recommended for use with slugs. Is there a specific reason for this other than further narrowing the potential area that will impact?
I would think that because full choke reduces the spread of shot it will not work with a slug, because a slug is a single round and has no spread. So you will not get any benefit.
The Battlelog description is
Significantly tightens the shot spread for improved Accuracy, but has penalities for Stability and Hip Fire as well. Not recommended with Slugs.
So coupled with a slug, you would not get any benefit from the reduced spread, but you would incur a penalty to stability and hip fire.
The Full Choke is a weapon attachment featured in Battlefield 4. It tightens the spread of buckshot or flechettes. It improves the ADS accuracy, significantly more than either no attachment, or the Modified Choke. As with any shotgun choke, it adds an increase to recoil.