The difficulty with this question is that the act of chucking is a very specialized skill that is nearly unique to humans. While some primates can throw things to a degree, only a human can do so with any degree of accuracy or consistency. So, to create an estimate, we must consider the woodchuck, in proportion to the size of an animal that CAN chuck wood.
An average woodchuck is 1’8” tall, 8.7lb, and can throw an unknown weight. An average adult man is 5’9”, 179lb, and can throw about 30-60lbs. Woodchucks have a slightly shorter arm-to-body length to humans but a slightly more muscular physique. Since we are both mammals, it is suspected that woodchucks would have a similar throwing capacity to an equivalently sized human.
To determine how strength would scale, our expert data analysts have deduced that the strength of an animal is based on the cross-section of its muscles rather than volume or mass. Therefore, strength should scale as a square of the change in height. Since a human is 3.45 times as tall as a woodchuck, it serves to reason that we would have about 11.91 times the muscular cross section. If these estimates are correct, then we believe that an average woodchuck could chuck about 2.5-5 lbs of wood.