Shooting KSG stops iron sight aiming

[Elaboration]

Hey guys, just a small inconsistency I've noticed amongst my games:

For reference, I have Right Mouse Button set to Iron Sight, *not* toggle iron sight. Holding Right Mouse Button lets me just Left Click repeated and stay in iron sights, with the pistols, assault rifles, the combat shotgun, the AA12, etc.

Sometimes, shooting the KSG while iron sighted takes me out of iron sights, so I'd get one aimed shot off and then my view would revert to hip-shooting, even though I still had the Right Mouse Button depressed.

I consider this a bug rather than a feature, because other times the KSG will let me continually shoot while ironsighted, without taking me out of iron sights.

Thank you for your time.