Author is you are not busy with something then I'll wait till you answer...no need a rush.

[[ArcCW] Black Ops Pack] lua/arccw/shared/attachments/ubgl_aug_mk.lua:145: attempt to index global 'att' (a nil value)
1. unknown - lua/arccw/shared/attachments/ubgl_aug_mk.lua:145
2. GetBuff_Hook - lua/weapons/arccw_base/sh_attach.lua:194
3. unknown - lua/weapons/arccw_base/sh_think.lua:309

I know some other players are getting it too but I hope Author can investigate it then see what went wrong. I haven't test the shooting because it that error.

I've added this Masterkey(BO1) in Blacklist till it further fixed till then I hope you get it fixed soon!