Remember when doing a LP model, all the edge loops should go towards keeping a good and smooth silhouette. All the loops that don't help the silhouette should be deleted. EG. all the edge loops on flat surfaces can and should go, it's ok to have a few edges meeting in the same vertex. Those parallel edges in the front part…
He already has a smoothing break where the trigger guard meets the grip. You're right about the rails, he could probably keep those as one solid chunk and collapse the loops like gsokol pointed out. Detaching them wouldn't really save that many polys.