Found the factory manual for the SSG 69 models. Trigger adjustment is on page 31 & 32. Steyr says the double set trigger is set "optimal" at the factory and should not be messed with. Probably lawyer talk.
Since you are a new SSG 69 owner, just a couple of important tips:
- Be VERY careful with what solvent you use for cleaning. Use only Hoppes #9. Other stuff out there will eat the polymer stock, mag well / trigger guard and mags. That can be a VERY EXPENSIVE mistake to make. I have used Hoppes #9 without issue for years, but I am still careful with it. Lube and a light wipe down with Break Free CLP will keep it running and looking like a champ.
- Loaded magazines: DO NOT drop one! The rotary mags are one of the weak points for the SSG 69. They are fragile, expensive to replace and spare parts for them are like hens teeth. They work, but you have to be careful with 'em.
I read your post about optics. You were given a great original setup that a bunch of current and future SSG 69 owners would strive to own. I hope you decide to leave it that way. The value of these setups are only going up.
Enough babble. Here is the manual:
Steyr SSG 69 Owners Manual