The three mentioned seemed to hover around the 7 lb. mark. If the receiver is the same as a 16 and a 20, it stands to reason the barrel will be profiled a bit heavier, for that reason and 28 gauge pressure is likely a bit higher than either 20 or 16 gauge.
It doesnt appear they were ultralight. There are bunches of fakes, too.

No connection to this one:
https://www.gunsinternational.com/guns-f...un_id=101464653

Best,
Ted