If you use a barrel mounted sling swivel under tension for shooting support, especially a sling with an arm loop I would imagine there would be a strong sideways force on the barrel. Doubt it would break or permanently bend anything but it could pull the barrel to the left (if shooting right handed) and throw accuracy off. Could it pull the breech open with a small downward force from the sling? Or it may not be an issue a all, I don't know never tried it.