What Kuduae had to say is 100% accurate. In gunsmithing school, we re-regualted a number of double rifles and drillings, doing essentially what Kuduae explained. Later, personally, in doing the same, especially on several shotgun to double rifle conversions I made,some re-regulating them for scope use, and/or for other cartridge loadings, I did same. As a result, I now prefer to leave wedge a bit long, without trimming it down to barrel muzzles, for possible future re-regulation work, as that makes for a much easier proposition than cutting a new wedge and fitting it.