The flat bullet is designed to clean out the end of a rod if dirt and debris have built up there. You will find one of these attachments in each rod set, usually described as a thread cleaning flat bullet. If used regularly it will prolong the life of the rod set.
Over time, the female thread of a rod can become blocked with debris and dust that has collected inside it. This means that the rod will not be able to be fully mated, or screwed together, with the male thread of another rod. So, the rods won’t be fully connected together when in use and may come apart or break.
The flat bullet has a cross drilled into the thread.
By repeatedly screwing the flat bullet into the female thread of a rod, and then taking it back out, any debris collects in the voids created by the cross in the thread of the flat bullet.
Simply tap the rod onto a solid surface and the debris that has become dislodged will fall out of the end of the rod. Once this debris has been dislodged by the flat bullet attachment, the rod can be used as normal.