I can't point to any authority on this, but I believe the rate of twist also plays a role. Doubles have a relativey slow twist rate - around 1:19 - 1:21. In my experience, bolt guns have a much faster twist rate.

In a typical double, the bullet makes a little over one revolution, where it make two or more in a bolt rifle.

That HAS to have an impact on pressure. And it seems that more pressure would equal more recoil. The difference between feeling a hard push versus feeling a sharp bang to the shoulder.

Just a thought, and my 2 cents (3 cents Canadian).