When I started shooting with air rifles some fifty odd years ago I only ever shot standing. When I returned to shooting a few years back many decades of standing on my feet in rubbish jobs had taken their toll on my back, shoulders and hips and I couldn't hit a barn door from twenty paces. I kept at it modifying my stance and hold, swallowed my pride and started to practice from 10 yards and gradually working my way up to 15, then 20 then 25 ( my standard practice range ) and upwards. I can hit a 2" target now at 50 yards free handing with a reasonable percentage of success, after many months of practice, but I find that comps pile up their own pressure due to unfamiliar targets and surroundings and uneven ground so hitting a 30 mm target standing at 35 yards is actually quite a challenge. Practice, patience and familiarity with the gun is the only way to improve.
A.G