[mapsjanhere]

If the loads are what's typical for the gun, you're not unlocking during firing. Since you can manually operate (what's done comparatively slowly) something is jamming your ramp and prevents the barrel from tilting. Check the gliding surfaces for some roughness to see if the barrel moves back but hangs up during firing. Your loads might be right, just a drop of oil in the right spot or some strokes with a stone might do the trick.