When using Grendel w/ Silencer. If you switch the fire mode then the silencer will be malfunction. And so far you can only fix this by switch Grendel back to 3 burst firing mode. And also, sometimes this silencer malfunction bug will also makes you can't aiming down the sight for couple seconds.
The silencer bug on the grendel in single shot mode svcks..... I only use the grendel in ss and now its useless without a suppressor. The feline has no problems in ss mode with silencer. I hope its fixed in 1.3 patch