Yes, those other 'forces' act to reduce the velocity of the bullet, and therefore the recoil. Also there are forces operating in all directions, however, the only directions that allow motion (hopefully!) are in the direction of the bullet and the reaction in the opposite direction to that of the bullet (i.e. the 'recoil').
Most of the recoil is due to the bullet. Of course the gas itself has mass, but a 'blank' has much much less recoil than a 'live round', even with the same powder charge.
Most of the recoil is due to the bullet. Of course the gas itself has mass, but a 'blank' has much much less recoil than a 'live round', even with the same powder charge.