According to the compiled data in The Parker Story, the vast majority of Parker Bros. .410-bore doubles were made in VH-/VHE-Grade (469) with the vast majority, 463, with 26-inch barrels. Probably a bit less then 100 in all the higher grades combined -- 4 in PH-/PHE-Grade, 28 in GH-/GHE-Grade, 60 in DH-/DHE-Grade, and 6 in CH-/CHE-Grade. As a point of reference, at the Las Vegas Sporting Arms Show in January, one of the big dealers had a GHE-Grade .410-bore on his tables with an asking price of $41,500. I know of it selling for $15,500 about 5 years ago.
Parker Bros. .410-bores are no where near as rare as some other variations such as factory original Magnum-Tens, but the feeding freenzy they cause among the faithful is something to behold!!!