I agree with all that has been said so far as possible reasons for your problem. One additional possibility is OAL. Have you checked the distance to the lands for your loaded shells in the Encore vs. the Ruger? It could be possible that if you have seated the bullet to where the Encore likes it, you may be up against the lands in the Ruger. This would cause the bolt to be hard to close, and could cause a dangerous pressure situation. Chances are that if the shells will magazine feed properly in the Ruger this is not the case, but it is worth checking anyhow.
James is right about case length, also check carefully.