My son turned 10 years old today and he wanted to go shooting.    I took the opportunity to take some of my other guns out (besides his Savage single shot .22 and my 10/22) and I had 6 rounds of USGI LC 11 headstamp M855 to run over the chrony.  I put the chrony about 12-15 feet from the end of the rifle (20" Colt, 1/7 twist).  5 out of the 6 rounds registered at 3400 fps or faster, one registered 3399 fps.  Isn't 855 supposed to be around 3100 fps at 78 feet from the muzzle?  Granted, I was closer than that but it doesn't lose that much velocity in 60 feet does it?  Temperature was low 70's.

Something is wrong. M193 doesn't even do that.

Your chrony was probably too close. As I understand it, if it's not far enough out the plumes of gas at the muzzle can cause phantom high results.

Really?  I didn't know that.  I'll have to check that next time I go out.  I sure hope that's all it was and it's not something wrong with my chrony.  Guess I'll have to check my reloads as well.  

Thanks for the info.