A foam-type insulation material may be added to the fiberglass replicas. It is inserted in the cavity between the outer casing and the bore.
This procedure is in part for acoustical reasons. Without the insulation, tapping on the cannon will produce a slightly hollow sound. The insulation will further add a little weight to the gun and even a little strength, though is not necessary to the integrity of the piece.
Insulation is an option, available at an additional cost, and is notpart of the standard production methods. If desired, extra bulkheads can be added instead of the insulation. This would give the piece added strength to ensure even greater durablity. The bulkhead reinforcement price is the same as the insulation price. I would recommend the bulkheads for added durability. For even more strength additional fiberglass can be added. call for a quote.