Hi Vitor
That particular wagon is at Haustenbeck proving grounds so not a front line example. Clearly if one were to model it as is, striped poles (of whatever colours they are) would be correct but the one you built is a different example. The giveaway that the ones on the model are cleaning rods is that one end of each of them has a projecting parallel-sided screw which attaches to the other end of another rod like a drain cleaning rod. As noted, the barrel is quite long but it is also quite high, so no doubt quite a few sections were necessary to allow enough crewmen to use it from ground level, hence the brackets being on both sides.
Since ranging rods stick in the ground, they have a point on one end, which these don't.