There is more windage in my mortar and popcans are very loose in the bore. The little 4 oz. sliced mushroom and slice olived cans are a much better fit. The wire loop only needs to come up out of the cement about a 1/2 inch and I only fill the cans up to within a 1/4 inch of the top and tuck the streamer part way under the loop to hold it during ignition of the powder charge. When the can is in the air the streamer will unfurl on it's own. The smaller cans use less powder to go as far as the bigger 12 oz. cans.