I always got around using springs for all kinds of stuff in Lego models cause they are generally not made for them. I was so wrong! There ARE springs made by Lego, though they aren't useful for projectile acceleration due to their low power. That's true, but I never thought about using them for all other non-shooting functionalities of a gun. And that's were come in and get useful! I found a spring lying round while I tested my "jointed" rack and made a very basic but excellently covering grooves along the whole trigger group. I wondered how I may be able to setup all the stuff without rebuilding and saw this little spring lying there. So my question was: why not use these springs to lock in combination with the rack instead wrapping around something? Soon I discovered some more sturdy and chainable springs I got from an insect alien set and now there's a long double springlocking the action as it should be for a proper break-action. You can simply break it by hand, no need to press a button push some lever. It's like I always wanted it! Now that's a success I say you. Far better than the other versions, very comftable! So now that this is solved for the lasting rest of eternity, I can FINALLY add a sight system.
Geez, that took kinda long. But as I always say, the way is the goal. This time the way taught me how effective technically simple solutions can be (as always, most simple things are better than their complex counterparts). Oh and maybe a safety measure of ensuring the locking doesn't open accidently is a good idea. I already opened it by mistake, so practising errors always shows that are things to be done.