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Posted: 9/30/2011 10:25:52 PM EDT
Downrange, & trying to calculate the actual boresight distance using a non-standard method. Given what members have observed from their ARs w/ 14.5" bbls, what is the actual MV velocity I should expect from M855? 2900? 2970? Or less? If you have chronographed it, please @ least tell me if the # you give is corrected for the actual distance of the chronograph.

If I have to shoot this thing, it'll be @ all of 20 ft, & in the 70's. It's getting quite pleasant here @ night. Yes, I've checked the Ammo Oracle - it gives # for 16" bbls.

Farmers Fight!

backbencher
Link Posted: 9/30/2011 11:41:08 PM EDT
[Last Edit: 9/30/2011 11:49:02 PM EDT by Jolkm]
In general, M855 has a muzzle velocity a little under 2900fps from a 14.5" barrel, which is about 80-100fps less than from a 16"bbl. Somewhere at this site there was a ballistics chart for a few different rounds from 14.5", 16" an 20" barrels for comparison, but I don't remember where.

ETA I think this was it, but the pictures are gone for some reason.

http://www.ar15.com/content/page.html?id=173

Maybe someone should contact the site staff to let them know the images are missing, but I'm to tired right now.
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