Q: Can you use the not yet released “Realistic Weapons Pack” for commercial use ?
A: Yes, you will be able to do that when it’s available. Also, you can use all of the free Epic content in the marketplace commercially in any games you build with UE4. This includes all of the content residing in example projects. For example, all of the weapons, meshes, sounds and materials in Shooter Game. Tappy Chicken even!
hope that helps