[B. Dudley]

Not so much a RELOADING question, but I thought this might be the best thing. I took my 12g 1880 grade 2 lifter with 32" barrels down to the club today and shot a round of skeet with it. First time shooting it much. I was shooting RST lite 1oz loads of 7 shot. Factory loads. I noticed a lot of unburned powder in the bores. What might cause that?