Ignoring buckshot, shotshell pellet diameters can be determined (other than measuring) by subtracting the shot size number (expressed as hundredths of an inch) from .170”. It’s easier than it sounds.

.170” - .09” (#9 shot) = .080” pellet dia. for #9 shot
.170” - .06” (#6 shot) = .110” pellet dia. For #6 shot

Larger (heavier) pellets retain more energy at longer ranges and penetrate deeper.

Dram is a black powder term for volume that has been loosely carried over to smokless shell by the manufacturers. 2-¾ drams of black powder has the same volume as 1-1/8 ounces of shot. You could use the same dipper to measure shot and powder for your 12ga (2-¾ drams FFg, 1-1/8 oz shot), which is equivalent to a standard 12ga target load today (about 1200 fps). Loosely speaking, the higher the dram number, the hotter the load.

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The 2 1/2 would be the dram eq. My mistake

Thanks guys!!

Well that explains why some of the old shells I that I shoot every so often have so much wack to them.

4-1 1/8-4

41/4-1 5/8-4

old paper or slightly newer roll crimped plastic shells. They make nice fireballs out of the 18" barrel