Bozo

you will never elevate this problem with this size bait unless you pour the belly then close the mold and pour through a "new' top or back area sprue gate that is deep enough to allow the natural contraction of the cooling plastic to take place in the pour sprue/gate area of the the bait,which would happen outside of the cavity area if it were the highest part of the back side of the mold. the reason is that most of the contraction will happen where the heat dissipates last. Hope this makes sense to you