But, if you are shooting a game gun at Bobwhites at 25 or 30 yards with standard American loads (3/4 and 7/8oz at about 1175 fps) then there is very little difference.
Mike, methinks you don't read so very well. If you go back & check my first post on this thread I believe you will find I basically said just that. That is comparing "Just" those two loads. Things went on from there in discussing the total difference between the two sizes.
As to the 12ga I believe if you check you will find that the standard load for the 2 5/8" shell was 1 1/8oz prior to WWI. The 1 1/16oz load came about as a legal restriction during the "Great War" in England, it has never ben a standard in the US. The "Standard" for the 2 3/4" was 1¼oz & British guns with 2 3/4" chambers are so proofed.
Note also I have absolutely nothing against a 28ga, If one serves the desired purpose Great. The Question concerened the "Differences" between one & a 20. I have tried by level best to acurately describe those differences without being interferred with by "Emotions" but rather by ballistic facts.
If you read Burrard (My favorite authority on the shotgun) you will find he rates the power of the various gauges as being proportional to the load of shot they fire. I rated them as proportional to the Sq Root of their charges. Thus he would assign the 7/8oz load as being 16% superior to the 3/4oz, while I only gave it 8%. Burrard would thus assign the 20ga at 35yds in comparsion to the 28ga while I only gave it 32½yds.
Really I fail to see your problem.
