777 creates a crud ring, this is why your having the problem your having.take a mixture of 50/50 windex/alcohol and apply a small amount to a patch ( don't saturate it) and swab between shots.swab pull patch out and flip it and swab again and your problem will be solved. do not continue to shoot the rifle if the bullet isn't seated firmly on the powder. IT"S DANGEROUS and could possibly bulge or blow up the barrel.