Runar, you've done a fantastic job on that old pistol - looks like it is brand new from the Gunsmith's workbench.
Are you going to test fire it? I know I would, even if it were only one shot.
From another post, maybe two years back, you showed using that rubber tubing as a clamp for wood joinery. Got me a 25' (about 8 meters) piece of 1/4" (6.2 mm) real stretchy rubber, and have used it several times. Used to have a radio controlled glider model that used a 140' (43 m.) piece of that tubing as a launch for it. Never thought that years later, I would be using the same type of tubing on gun work.