A 410 saiga is little differant. The barrel is shrouded on the top over the bullet guide to feed the round. I have one Ill post some picks later.
Im planning on doing a 410 barrel possable for my switch barrel build. also now planing a smokeless powder muzzel loader barrel for it as well.
brass shotgun shells can be had and can be made rimless and would allow a standard bolt to be used if opend up to 308 win sizes. 444 marlin brass can be converted into
410,and even 30-06 brass can be converted into rimless 410. I sugessted a 410 SGFH type round with a protruding .45 rifle bullet here a about a year ago.