I found a 100 pack of M855A1 bullets today at a gun show. I decided to pick them up out of curiosity
I weighed out a sample of 20 bullets and found that they were rather consistent with weights ranging from mostly from 61.8 - 62 grains with one at 61.7
You should expect them to be a bit more accurate than the old M855 green tip. The steel core in the old M855 is what makes it less accurate. It’s not an inherent accuracy disadvantage, but a matter of manufacturing difficulty. If the core is not perfectly centered it throws the center of gravity off and you get wobble. Ever get that tight 4 shot group only to have the 5th go wild…and you know you didn’t pull the shot? With the old M855 that’s usually why. That is part of the reason that M855A1 is more accurate (and I can tell you that it definitely is…although still not the round they should have chosen, but that’s a whole different topic).
There have been a couple indurations of the “A1” rd. Due to assorted program issues… I have seen Army types with a light grey, med grey, and near black tipped projectiles. Not sure which is the latest, or what the final composition turned out to be.