ar-15 velocity

[partisan1911]

I picked up some black hills 77gr ammo for my ar-15 with 16" barrel. I was getting velocities of 2495-2500 fps, 20 degrees outside temperature. The factory velocities are estimated at 2750. Do my velocities sound normal? What length barrel were they testing their ammo through?

 

[eli polite]

Re: ar-15 velocity

length of barrel, altitude, type of rifling i think polygonal rifling allows for better speed and a bolt gun vs. a gas gun

 

[zinny]

Re: ar-15 velocity

if i remember correctly, going from an 16" to 18" barrel correlates to over 100fps increase. but from 18" to 20" you get only 50 or so.

 

[partisan1911]

Re: ar-15 velocity

So my velocity sounds about right for today? It is 20 degrees today with low humidity, elevation about 1000'. I am probably using a shorter barrel than black hills tested with.

 

[boltcatch]

Re: ar-15 velocity

Sounds right to me.

 

[spr1]

Re: ar-15 velocity

Their velocity is probably specified for a 24" barrel

 

[Rovieairto]

Re: ar-15 velocity

With handloads I am safely getting well over 2600 ft/sec with the 77 SMK in a 16" barrel.
The mk262 military load will is in the 2700's out of the same barrel.