"Every action has an equal and oppossite reaction"
That weight sliding foreward would repel the gun backward, making the recoil worse. Allowing the barrel itself to slide back would do better if you must have something sliding and that would handle the recocking action. The muzzle break seems to be doing the right thing, good job there. As a last note, the handle and especialy the trigger look a bit small.
yeah, i actually drew the as if it had been fired (it slides forward to counter the recoil). the handle and trigger could be small, im not really sure (i didn't really reference anything for this gun, so that could be why.)