Came across a bug recently with the new IR laser/illum mod and running Auto rifleman with the 249. I have gotten the new IR laser/illum to work properly on the M4s after realizing I had to unbind the vanilla laser so they both wouldn't fire.
However, on all modded IR lasers and on all 249 variants, only the IR illum works properly. The IR laser beam seems to collide with some part of the 249, creating the IR "bloom" where the laser usually hits an object, but it is just at the gun itself. The illum and vanilla laser still work properly, but it's just annoying to have to rebind which laser I want to use each time I run rifle vs autorifle. Thanks!