I purchased a hornady 38/357 die set from the local loading shop today. they were out of rcbs which im used to. I was given some "double sided" wad-cutters. Iv never loaded this type of bullet before.... does this take a special seater plug? I'v never used these dies. any help would be great!

Double sided or double ended? Anyway, I've never used a special seater for DEWCs, the seater plug in my die set is for round nose bullets, it works fine.

Your Hornady die set should have come with two seating plugs. One with a concave end, and the other with a flat end. Use the flat-ended one.

Andy

the bullets are double sided/ended. load either direction. the hornady die set i purchased only came with one seater plug.

Either seater will work with the WC nose shape. The difference in seater plugs is to "fit" the seater to the nose geometry of the bullet and help keep pressure spread evenly on the bullet as it seats. This keeps it from cocking and seats to a more even depth.
The wad cutter design doesn`t really have a "nose" and the lip of either seater plug will contact the bullet on the flat shoulder area evenly during seating. They normally will seat to a much more precise COL because of this then HP, SWC`s or HP bullets.