These are are BAM19's (SMK XS19). You will need a top hat, spring guide and stepped block that fits between guide and rear metal end block. If you like the look of the thumbhole stock and shrouded barrel on the Benjy, it would probably be cheaper to pick up a tatty XS19 and swap the action. The barrel diameter on the Benjy is slightly smaller than the XS19, so the shroud won't fit over it