Shooting short barreled or light weight guns takes a completely different approach for me. I can not do sustained, methodical type leads or use a swing through approach either. And spot shooting is a disaster for me. I end up with a shorter swing and aggressive swing, using shorter leads and moderately faster gun movement.
I have tried extra weights taped to or clamped to light weight guns with mixed results. What is the point of making a five pound gun into a seven to eight pound gun? I have a .410 hammer double, which tips the scales at just under four pounds. Shooting it like it is seven pounds is impossible for me. I shoot it like we use to shoot skeet, with a semi low gun starting point, gives me a lot of natural motion with my body, hands and gives me a clear vision of the birds. I just move the gun to meet my eyes is the best way I can explain it. And I am semi-aggressive, with short leads for best results. A dead gun is a certain miss for me with any short barrel or light weight gun. Plus I love tight choked small bores.