I thought that might be the case -- or at least something like that. But you could get a spare cylinder lock screw (gas plug) from Brownells for $13 and drill a good-sized hole in the center. Then you could shoot any ammo you want.
Better yet buy a schuster adjustable gas plug and you can just back the adj. to make it a single shot.this has the added benafit of allowing you to tune it to modern hunting ammo and not bend the OP rod.
to those that say autoloaders have no place hunting.I watched a "former" hunting partner empty his bolt gun at a deer at 250 yards of course the last four were running shots at an ever increasing distance.as soon as it was empty he starts digging in his pocket to try a 600 yard running shot I guess.
Hunting ethics as does Safety in general has NOTHING to do with the firearm.