Thank you for this information. I recently bought a .177 Supersport at auction (AR08701) ... auction caution applies! Ok the power as bought was not bad, c 700fps but the breech seal had degenerated and I knew the Supersport was capable of more. A new one added about 10fps. So it was stripped ... broken mainspring. Fitted Titan No 1 as listed to fit. First try: way 'too much spring', so gradually cut spring down coil by coil to give a pleasant 11.4 with JSB 8.4. Piston seal looked fine.
I was surprised to find a plastic tube piston liner present. Also has the Maxigrip rail and a breech bolt not pin. Does this make it the Custom version?
Unfortunately the open sights are missing and I do not have any in the 'bits box'. So I will keep a look out for some. Otherwise, cosmetically not bad.
Cheers, Phil