Hi Oliver
I own a Superstar in .177.
It is an underlever rifle with the same rotating breech that is used on the last of the Airsporters (RB2's)
The spring has to be compressed for the alloy breech unit to rotate
The trigger is excellent and far more sophisticated than on the Airsporter.
I believe the trigger unit is shared with the Supersport and maybe the Lightning
Stocks are beech and although they have an attractive shape, the finish is a soft laquer(possibly cellulose) which is easily scratched
The .177 will give 1" - 5 shot groups at 50 yards, so it is an accurate rifle
Power and accuracy'out the box' was very good, and the piston head looks like nylon(similar to the FWB 124/127's)
Mine is 10 ft lbs with the spring fitted and almost 12 ftlbs with the Theoben gas ram fitted. Unfortunately the gas ram makes the rifle more difficult to cock but accuracy is still of the order of 1" groups at 50 yds
There is a full length and a carbine model and the guns have a potential to develope high energy levels, particularly in .22 by the addition of piston weights
The Superstar has the excellent scope dovetail fixture developed by BSA
When they were discontinued, Superstars were getting on for nearly £300 so they were not cheap to buy but are a quality gun and probably one of the best air rifles ever made by BSA