I hate to break it to you, but the whole "speed pump" thing is pure marketing. I'm pretty sure world records have been set with the Benelli (its the Indian, not the bow), and my Wingmaster does the exact same thing. When the gun fires, the fore end/bolt is free to travel to the rear. Recoil throws the whole gun backwards, you stop the butt, and inertia keeps the fore end assembly moving.
As long as you are happy with the gun, that's all that matters. Enjoy it.
What could have happened... did.