For the pack normally I clip it to the hammock suspension.
Since I don't hunt I am not sure, but I can see my uncle who is an avid hunter take a gear hammock and put it in there wrapped in a a piece of oil cloth. At least I think that what they used to wrap firearms in, in the olden days.
That is what I would do cause of the odd size and weight/position of a rifle instead of trying to hang it off of the suspension.
I hope my rambling helps a little.
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