I have a 40-65 with a .410 bore and I have quite a few .412 sized bullets with a gas check for hunting.  I have since acquired a 40-70 with a modern barrel with a .408 bore and have pulled the 40-65 barrel off of the hiwall and put the 32-40 barrel back on.  What kind of problems, if any, will I have shooting the larger bullets in the smaller bore with blackpowder?  The bullets chamber easily in unsized cases.  Thanks.  Tom