I thougth when I did my test, I had a chrono along, but I guess not.
anyway, these are the results of my first testing for AR-15 functioning.
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I got to the range with some 62gr HM² (.226/SL68B) loaded with H4895 for 556 AR (1:9). This was just a test to see what cycles the action. I loaded about 6 rds of each. 18gr. 19gr. 20gr. 21gr.
the 18gr didn't eject the brass
the 19gr ejected the brass, but didn't cycle a new round into the chamber...except the last round, which jammed.
the 20gr cycled as it should, but seemed slow, like a howitzer.
the 21gr cycled perfectly.
This is a brand new DPMS gun, so spring and action may be stiff.
I was shooting off-hand at 25 yards in the pistol pit, all 6 rd groups were 1 to 1.5" with a couple called fliers. so, not a good test of accuracy, but I've seen lots worse in other guns when boolit was poorly matched to load and/or gun.