Should have no problem at all smoking 100% hickory. Sonny was correct, the labels can be misleading. Most of the cheaper pellets (Pitboss, Traeger, etc) use a blend that may be only 30% hickory or flavor wood. Most of the better pellets (BBQer Delight, LumberJack, etc) make pellets that are 100% of the wood shown on the bag., though of course they are more expensive. That said, they also make blends so you really need to read the label. 100% hardwood hickory is not the same as 100% hickory.
Regardless, try different brands and types till you find what you like.