I had often wished that the best of the BT99 plus and the BT100 were combined in one gun...a 99 plus with an adjustable drop out trigger would have made it the most awesome working mans price range trap gun out there
The basic differences between the 99 original/standard model and the 100 are the removable trigger and the higher rib of the 100. The 100 was also often ported. They made a gloss and a matte finish model, with the matte offering only extraction of the empties, and the gloss offering selectable extract/eject. The last itteration of the original 99's (the 99-Max - - had a higher rib but no drop out trigger)...it was also select eject - ejecting the fired hulls, extracting non-fired shells. As mentioned above there were also 99-Pluses...these shotguns had adjustable, higher profile ribs, a recoil reduction device with "somewhat" adjustable butt-plate and an adjustable comb as standard. They were also only Invector Plus choked and offere in ported or non-ported. The "newer" 99's were reintroduced after the BT-100 was discontinued.