>>3688639pic related, a nra high power competitor you retard. and yes, you can attach a sling to a lens, anything big always has attachment points. if you werent larping you'd realize that the sigma 150-600 you supposedly have, has them on the tripod collar.
and regarding $8k and over optics, look at anything thermal, or some night vision ganged to a daylight scope. and people dont carry them in a case as it defeats the purpose of a carrying a rifle.