Might also be the rim cut on the rh barrel is a few thou. deeper than on the left bl. If the ejectors are in time, both shells should pop out after firing when you crack open the breech- You might want to slide out the luggers from the breech tunnel and clean all that area with Hoppe's- and put the flats of the luggers on a flat Arkansas sone and remove any burrs- akso check the tunnel with a Q-tip for any burrs or debris-- Rim might be a shade thicker on the older paper hulls, allowing the shell to sit in the rim cut to give positive contact with the firing pin.
Never owned a LeFever Nitro or any of its clones, but, like the NID Ithaca, they are a very solid and well designed utility shotgun. RWTF
