Maximum velocity from 556 16" barrel w/77gr bullet

[ronas]

I chronographed some loads yesterday.

Using 77gr Nosler Custom Competion bullets,CCI 450 primer, 24grs. of Varget. Rifle is 556 OBR with 16" barrel. Velocity averaged about 2450 fps. <span style="font-weight: bold">Is that about the most I can expect with a short barrel.</span>

Have only shot load at 100 yards and 600 yards. At 100 yards I shot 20 shot group which was one MOA, as usual I had two that were a bit out or it would have been a little better than 3/4 MOA.

On the 600 yard target I only shot three rounds which I know estabilishes nothing. The wind was only 5mph but it was swirling. Three shot group would have been about 2 MOA.
I needed 19.5 MOA to get there and that with 64 degree temp, bight and sunny and wind mentioned above.

I also shot 20 shot group of 69 Smks at 100 yards and got 1 1/2" group. Velocity was about 2650 using CCI 450 primer and 26.6 gr of varget.

 

[spot69221]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

Should be able to get 2700fps, but don't let the chrono dictate the 'real' speed. At 600yds you should be able to get the drop figured out in JBM (or other program) to match the velocity.

 

[SJshooter]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

Have you tried other powders? Using a faster powder would result in more fps. Also, is that a compressed load? What is your OAL?

 

[ronas]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SJshooter</div><div class="ubbcode-body">Have you tried other powders? Using a faster powder would result in more fps. Also, is that a compressed load? What is your OAL? </div></div>

Yes, several other, including 748, blc2, reloader-15, Alliant 2520, H335.

Varget load is compressed, please note cci 450 is small rifle magnum primer.

None of the other propellants produced as accurate a round as the varget.

OAL is 2.250 and OG is 2.850

 

[Pusher591]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

Since you reload check this thread out. Same BC as 77 SMK but velocities of the 69...what's not to love

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2334672&gonew=1#UNREAD

 

[ronas]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pusher591</div><div class="ubbcode-body">Since you reload check this thread out. Same BC as 77 SMK but velocities of the 69...what's not to love

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2334672&gonew=1#UNREAD </div></div>


That link provide a lot of interesting reading. Thanks

 

[Pusher591]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

No problem, I thought it was interesting too. Him seeing those velocities out of an 18" gas gun made me wonder what you could do out of a 21"-23" bolt gun.

If I could run it at 3100+ that would be insane.

 

[poke5353]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

Might check out alliant ar comp or alliant pro 2000. Seem to have good velocities.

 

[BCP]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

OBR barrels seem to be kinda slow but 19.5MOA come ups makes me think it's more like 2550fps which would be more realistic.

FWIW the ultra match 16" I got from rainier is about 2600fps with that load and my 16" daniel defense (no longer own) was closer to 2500. 18" white oak was 2650 and 18" saber chrome lined was 2600. All with 24.3 varget and 75hornady which is my works-in-everything-okay load.

 

[BCP]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pusher591</div><div class="ubbcode-body">what's not to love

</div></div>

The price per bullet lol.

 

[Conrad]

Re: Maximum velocity from 556 16" barrel w/77gr bullet

Good stuff on those 70's...have you tried H4895?