I shoot short heavy guns better than light, long guns. I think perhaps I do better with 32" or shorter barrel - as long as it has some weight. My DR with 30" tubes, at 9 1/2 pounds and the .69 English gun wIth 32" 1 1/8" BL., same weight, are about perfect for offhand shooting, for me.
Interestingly enough, the light, my little Musketoon is easy for me to shoot offhand - neither heavy in barrel nor much overall weight and the sights are WAY to close together - bulky too, yet I shoot it as well as any other rifle I have - go figure. Even though it doesn't feel as good as any other rifle, it gives equal or better results - again, I don't know why. It only does 1" for 5 shots off the bags at 50 yards. I have more accurate rifles that don't do as well offhand on steel, nor at 25 yards offhand on scoring targets. I haven't tried it at 50 yet, on scoring paper.