In the butt trap of a model 1924 M-S rifle I recently found an original 4 piece cleaning rod...and the size of the hole in the rubber insert indicates that this is all it ever contained (the hole for a 5 piece rod is larger)...so apparently whether a rifle contains a 4 or 5 piece rod does not depend solely on barrel length....although a four piece rod is just barely long enough for the M-1924 barrel.