Yes. Some Mk5 Sten butts were made from converted No4 butts and used the SHORT bolt (you'll need to think about that.....), while other butts, made new, used a standard longer bolt. It's all to do with standardisation........

BUT....., you could end up in a situation where you had short bolt butts but long bolts. Simple solution was to get the machine shop to turn some wood spacers. Glue in, problem solved