How do I check point of impact (POI)?

Michael McIntosh describes the technique in Gun Dog Magazine (April/May 1993, page 98.  It's NOT done by mounting the shotgun like a rifle, but by mounting and firing as you would at a straight-away clay or bird AT 16 YARDS. The distances, vertically and horizontally from the center of the pattern to the hold point, is translated/converted as follows: 1 inch  = 1/16 inch on the stock. If you need to raise your point of impact 2 inches, then you need to add 2/16 inche to the comb. If you need to move the point of aim (POI) to right 1inch, then remove 1/16 inch from the face side of the comb OR add 1/16 inch cast off (to the right) .

Just adding height to the comb can be easily accomplished with the many 'stick-on' or 'lace-on' pads, BUT it will probably move your eye (your 'rear sight') slightly to the left (cast off and not good for a righty) and may add weight to your stock changing the balance of your gun. 'Soft-comb Elevator pads' are sold by Southwest Shooters Supply (602/943-8595), Meadow Industries (434/589-5541), and RST.  It is also possible to have the stock bent, and several smiths and stock makers specialize in this service.

L.C. Smith guns were well regulated (both barrels shooting to the same POI) from the Hunter Arms factory BUT in the 40, 60, or 100 years of use, your gun may have been dropped, either denting the muzzle or bending the barrels. If the bore is not perfectly round at the muzzle, the shot pattern will be off-center OR in the process of opening the chokes, the smith may not have reamed the chokes in line with the bore. Barrel regulation IS checked with the forend supported on a rest, as you would 'sight in' a rifle. An off-center pattern is a bigger problem, but can be corrected by choke specialists like Briley, Curtis Wilbanks, or Ken Eyster, Centerburg, OH (740/625-6131).