Grits; Its not a dumb question. The whole rod is made of brass, usually solid, but occasionally you will see thick brass tubing used. If the rod is solid brass, it weighs a bit. That is why you can buy stainless steel range rods, ( usually tubing ), and aluminum alloy range rods, usually tubing, also.
At Friendship, and other big shoots, you will see several rods at the loading bench of most shooters, rather than just one. One will have a bore brush; the other will have a cleaning jag or swab on the end. The brush is used on humid days to knock loose scale and crud building up in the barrel. At Friendship, the valley's winds, and the Brandywine creek provide lots of humidity, so shooters learn to come prepared to get the crud out of the barrels between shots. Its a different matter at the Winter Nationals held in Arizona in late February( this weekend).