The reason I suggested that it might be more economical to invest in a new gun as opposed to spending $100.00 or more "opening up the chokes" is because the value of shotguns made by the Meridian Firearms Company varies considerably. The Standard Catalog of Firearms stated, "...Current values depend on model, gauge, grade and condition. Difficult to find examples in excellent condition as these were sold by Sears to customers who put them to hard use. In good condition their current values range from $250.00 for Plain Janes to $3,500.00 or more for top grades, of which few specimens are known."
If the value of the gun merits the cost or if the owner wants to use the gun for sentimental or other reasons irrespective of value, Briley Manufacturing Inc. in Houston, Texas has a reputation for good work modifying chokes; especially if the owner wants interchangeable choke tubes installed.