Sounds to me like the bone amount may be too high & causing it to stay in his stomach too long; thus increasing gassy potential. Not too mention discomfort.
My big guy Rivers actually can't have much bone at all; even with TONS of vegetables, he will actually get blocked VERY easy. Trust me you do NOT want that, watching him having gone through that was horrible; only warning was his poops had gotten very dry, hard & tiny, within the time frame of the next afternoon he was shootin blood along with the tiny compact stool.
Are you doing vegetables? Sounds like your boy needs help moving things along in a *smoother* way....the one and only warning my vet ever gave me about raw, was to make sure the dogs get a LOT of fiber and that that is one thing many raw feeders forget.
Some dogs need fiber, others not so much. But it sounds to me like your boy has a lot of bone sitting in his intestinal tract that's not moving along in a consistent manner.
What other proteins, ingredients is he getting in his diet?