Anyone know the true muzzle velocity of the M855 62 gn green tip ball ammo out of the M&P 15 OR?

TIA

I sure don't but Google might. Make sure you include your barrel length in your search.

thanks, I will..... Hoping someone actually measured it at the range

What you seek can be found if you Google "Molon M855 review"

(I don't want to post links to other sites.)

I've got a 16in 1-7 twist that delivers an average muzzle velocity of 2928fps with American Eagle XM855. Rated muzzle velocity 3104fps.

I suspect it will vary quite a bit depending on the particular brand of M855 ammo you are shooting. Some brands to me "feel" weaker than others plus judging by the direction of the ejected brass they can be quite different as well. Unfortunately I don't have a chrono to verify any of this. I've looked into getting a chrono but my home shooting range is in a wooded area and from what I've read not having a clear view of the sky would likely cause problems.

I measured 2978 FPS, average of 4 rounds from my 16" barrel.

Perhaps they are rated based on use in an M-16A1, with a 20" barrel.

That's pretty much what I chrono out of my 16" AR w/1 in 9 twist.
The 14.5 M4 I have does 2910 FPS (10 shots average) which is about right for the + or - 32 FPS per inch of barrel gained or lost.

Note:
Ammo used was Lake City M855, all same batch.

__________________
Hold my beer and watch this!