Forward assist does function if you have the bolt fails to complete return to battery, in that pressing it does physically move the bolt carrier....
Also things to consider, if you want heavier recoil, consider running lightest possible front end assembly, light weight RAS, aluminum outer barrel, and less accessories up front. The "recoil" you feel is the physical force exerted by the moving assembly slams on the back of the buffer tube and the jolt it imparts on the gun. The more mass the gun carries, the less you are likely to "feel".
