Just bought a Huntsman Mk2. The gun appears to be walnut stocked. I'm hoping to get my hands on it this week. I don't think parts are available any more, but hopefully nothing worse than 'o' rings........which leads me on to.....there doesn't seem to be any info on the web about 'o" ring sizes for the MK2. Does anyone know the sizes required or indeed have any more info on these?