It's more likely the thumb screw needs to be tightened to be indexed properly, however; it is possible that it was over tightened and simply needs to be turned back.

To date an Arrieta look at the four sequence number stamped into the water table and/or barrel flats.

Example: 57-03-205-07
*The 1st set of numbers (57) is code for the manufacturer.
*The 2nd set of numbers (03) is code for a shotgun.
*The 3rd set of numbers (205) is the number of the gun built in that particular year.
*The 4th set of numbers (07) is the year it was built.

The full serial number, in the above example, tells you that the gun was built by Arrieta, it's a shotgun and it was the 205th gun built in 2007.

Wild Skies
Since 1951