Shadow bleeding at corners

I am having some trouble with shadow bleeding in the corners of my model and am unsure how to correct it. The model is all one piece and the lightmap I have created is all spaced out correctly (I think - I don’t fully understand lightmapping!) so I am completely lost! Any help would be greatly appreciated.

could be a partial pixel offset on the lightmap. are you using your own lightmap or a UE4 lightmap generated from yours?