I have been carrying by this method since I had my older brother's oversized BB gun at age 5, and have never stopped, but I am damned careful about muzzle direction. I just find if to be more comfy than a strap digging into your shoulder, and if I grab by the muzzle, I find it super-easy to carry and keep the muzzle in a safe direction, and have ever had any issue with safety.

By contrast, I have seen a non-friend that I had the bad fortune to be hunting with "Barney-Fife-it" taking a gun off his shoulder that was carried via the sling. Glad I was some distance away and the gun was not facing me when he did that.

I guess you can be safe or unsafe, depending on you the individual

Psalm 19:14-May these words of my mouth and this meditation of my heart be pleasing in your sight, Lord, my Rock and my Redeemer.
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Humble servant of Jesus Christ. Living His plan and praying to show it in name, word, body, and light.