Do somebody know the secrets of the filling formula of them?
There were various materials, for sure lead shot, kiln dry sand, maybe latex or epoxy powder...
a special paint...
Personally, I'd fill 'em with concrete and for several reasons. But as things stand in the picture, I suspect it really wouldn't matter much what you do as performance differences should be pretty minimal regardless. As things stand in the pic. Even so, concrete is still still probably your best bet.
Personally, I'd fill 'em with concrete and for several reasons. But as things stand in the picture, I suspect it really wouldn't matter much what you do as performance differences should be pretty minimal regardless. As things stand in the pic. Even so, concrete is still still probably your best bet.
I see a business opportunity. A proprietary SOTA mixture of various cyro treated materials (lab tested for density of course) that substantially outperforms plain old sand, concrete, or lead shot. And sell it for $5.00 a pound plus shipping.