Saw this on a couple threads in the past with no definative answer. Did a semi scientific test and thought it might be worth sharing. The question was how much difference does shot size make on the weight of shot per a given volume, like a shot cup. I found a graduated cylinder (remember chemistry class) that was very close to the ID of a 12 ga shell. I slid in an RP12 wad. Put this on the scale and zero'd it. I had #1 buck, #4. #6 and #8 shot. I filled this with 15ea #1 buck, the top most pellets came up to the 6.6 ml line. I weighed this and then repeated the process with the smaller pellets. I filled to the same height everytime figuring that this was as tight as you would want to crimp the shell.
The results are as follows with #8 shot being 100% weight
#6 was 92% weight ,#4 was 89% weight and #1 buck was 80%. I put this on a chart vs the pellet diameter and saw a predicatable curve but am not smart enough to post it here. Just for grins I tried some #8 reclaimed shot, I was thinking this beat up shot might "nest" a bit tighter but it came in at 99% of the weight of virginal #8. So on the surface it does appear that when confined to the size and shape of a shot cup or bushing ,shot size could vary weight by 10%? Also if you weight the shot thrown by a given bushing going to a larger shot will reduce this a bit. This is a marginally scientific observation and has most likely been posted before but thought it fun to share.
The results are as follows with #8 shot being 100% weight
#6 was 92% weight ,#4 was 89% weight and #1 buck was 80%. I put this on a chart vs the pellet diameter and saw a predicatable curve but am not smart enough to post it here. Just for grins I tried some #8 reclaimed shot, I was thinking this beat up shot might "nest" a bit tighter but it came in at 99% of the weight of virginal #8. So on the surface it does appear that when confined to the size and shape of a shot cup or bushing ,shot size could vary weight by 10%? Also if you weight the shot thrown by a given bushing going to a larger shot will reduce this a bit. This is a marginally scientific observation and has most likely been posted before but thought it fun to share.