410 conversion

[Dean Romig]

OK, those are sub-gauge inserts and are likely removable. However, there is a distinct possibility the bores are so pitted that a previous owner chose to shoot the little .410 shells in it. But the more I think of it the more I wonder why he wouldn't just have used 20 ga. inserts in order to shoot an economical shell. So maybe the bores are okay to shoot 12 ga. loads and he just shot .410 shells part of the time and removed or replaced those inserts with inserts for another gauge or simply shot 12 ga. shells when he wanted to. You should take it to someone who knows how to remove the sub-gauge inserts and then inspect the bores and the wall thickness of the barrels.

[Double Play]

Nancy,
The inserts in your Parker are likely similar to the Briley sub gage insert pictured below. If so they should be easily removed but as Dean said be sure to have the barrels examined as the tubes may have been used do to pitting ahead of the chambers.