Parker Double Barrel Shotgun ID?

[ArtS]

I have a few English and higher grade Belgian percussion guns. THis one looks a little odd to me. The shape of the breechblock and the rear part of the barrel contour look different from any I have seen. It is possible it is an older flintlock that has been converted to percussion. It was common for this to be done in the 1840 era. I have a high grade Manton that was converted.

One thing I find odd is that there are no safety/blowout plugs at the breeches. These were pretty much standard for any muzzle loading gun by decent or better European/British makers.