Along the same vein, but a different site had a drilling up for auction. Rifle barrel was marked (but not as proof mark) as being .450 82mm and the auctioneers had this labeled as a 450 Nitro Express. I emailed them to say that was very unlikely on an older (Collath) drilling from the black powder days, and it was much more likely a 450 black powder express. Especially with a very thin profile rifle barrel. They did not update the description on Proxibid but perhaps did on their own site (I didn't check). Drilling sold for $2100. I cannot fathom touching of a 450 3.25" Nitro round in a lightweight drilling.

https://www.proxibid.com//Guns-Mili...el-Shotgun-Rifle/lotInformation/99019608