Not being the technical type today I did a quick comparison of these four rounds. Not knowing what the "proper" procedure is this is what I did -- started with a clean bore, fired 2 fouling rounds, shot one 20-round string, let rifle cool for 10 minutes, cleaned bore, and started the process over again. The rifle was a Bushmaster chrome lined 5.56 with a 14.5" barrel and a KKF A3 TakBrake attached. Chrono screens (2 ft spacing) were 10 ft from muzzle. Weather conditions: Clear sunny sky, winds calm, temp was 54 degrees F, at an elevation of 4950 ft. While only a total of 84 rounds were fired there were no failures to fire or failures to extract.
Quick Summary
SA Battlepack Avg 2939 fps E.S. 94
Win Q3131A Avg 2884 fps E.S. 57
Fed XM193 Avg 2991 fps E.S. 53
IMI M193 Avg 2957 fps E.S. 47
Complete Results (one 20-round string):
SA Battlepack lot 352 A 86
High 2985
Low 2891
E.S. 94
Average 2939
S.D. 29.3
Win Q3131A lot TD80
High 2916
Low 2859
E.S. 57
Average 2884
S.D. 16.3
Fed XM193 Lot 10
High 3017
Low 2964
E.S. 53
Average 2991
S.D. 14.8
IMI M193 Lot 00223/C
High 2982
Low 2935
E.S. 47
Average 2957
S.D. 11.2
If I had it to do over again and more time available I would have liked to have fired two different lots of each brand with two 20-round strings of each through a 14.5" barrel and a 20" barrel. Also I realize there is more to a round than velocity. For one accuracy was not measured. After doing this I have a better idea what a more "complete" test would cover. Hopefully this information is somewhat useful.