The suppressors of many guns (particularly in the Marksman and Apex DLCs) are improperly placed on many models. For example, the 5.56 suppressor on the SPAR-16S is heavily misaligned, with most of the barrel clipping through the suppressor.
This is on a handful of weapons that I know of, possibly more that I haven't been able to test yet. The Cyrus 9.3, SPAR-16S, and Mk20/C are a few I can think of off the top of my head. Most of the time (but not always), this is only visible in first person, with the third person model appearing just fine.
This also applies to a few scopes and most of the bipods on many weapons, including the Cyrus, and some are more severe than others. But this is a separate issue in itself.
This isn't game-breaking at all and is mostly just aesthetically displeasing, but it'd be nice to see some more carefully-placed models to get a more authentic feel.