No I agree with all of that but there's no wiggle room at all, nobody straight up lowers their weapon because their barrel is about to brush a wall, especially if you're in a combat situation. The way it's done in Insurgency Sandstorm is perfect imo, you can pull back your weapon a little bit before you fully disengage, and it's still determinate on weapon length.
Our weapon does have a gradual push-back, but it's entirely dependent on the weapon and its attachments.