223 ammo question

[RWF]

i have built a "F" class style gun. i use that term loosely. it has a WOA 20" 1 x 7 twist and it is suppressed. i have only shot it so far to 400 yards.

the black hills 5.56 77 OTM shoots sub MOA at 2850 pfs.

the hornady 75 5.56 super performace does really shoot as claimed at 2940 pfs.

but i can not make it group at all, it just seems to all over the place. at 400 it is all i can do to keep all my shots on the white poster board that put my 12" target on. any ideas?

i do not understand why they perform so very, very different.

[ShootfastRunfaster]

i have built a "F" class style gun. i use that term loosely. it has a WOA 20" 1 x 7 twist and it is suppressed. i have only shot it so far to 400 yards.

the black hills 5.56 77 OTM shoots sub MOA at 2850 pfs.

the hornady 75 5.56 super performace does really shoot as claimed at 2940 pfs.

but i can not make it group at all, it just seems to all over the place. at 400 it is all i can do to keep all my shots on the white poster board that put my 12" target on. any ideas?

i do not understand why they perform so very, very different.

My limited experience with .223 loading has shown me that different barrels like different bullets at different speeds.

The BH 77 OTM load uses a Sierra 77 SMK whereas the Hornady Superformance use the Hornady 75 BTHP. The bullets are very different in ogive shape and length of the projectile. The 75 Hornady is a lot longer than the 77 Sierra even though the Sierra is 3 grains heavier.

My match rifle is fitted with a Noveske 18" SPR barrel. It is 1-7 twist with PT rifling. I can load the Hornady 75 to about 2700 fps and get 3/4 moa performance or better. I can load the Sierra 77 to around 2800 and it will stay right at 1 moa.

I run a reduced load with the Sierra 69 SMK and it will run right at 1/2 moa. I settled on that load and it runs 2720-2750 fps and lines up with my dots in my Burris TAC 30. If I push the Sierra 69's beyond 2900 fps., I loose accuracy and end up with groups approaching 2 moa.

I tried the Hornady 68 at 2800 plus, and they would hardly shoot inside of 6 inches at 100 yards. I slowed them down to 2650 fps and they are sub minute.

I am still working up a load to get them to 2720 fps and will see if they give me the accuracy that I require. I can get the Hornady 68's at a substantially lesser cost than the Sierra 69's.

It seems that your barrel doesn't like the Hornady 75's at the blazing speed that the Superformance reaches. I suggest loading some Hornady 75's at lower velocities to see if your barrel likes them.

[Powder Finger]

i have built a "F" class style gun. i use that term loosely. it has a WOA 20" 1 x 7 twist and it is suppressed. i have only shot it so far to 400 yards.

the black hills 5.56 77 OTM shoots sub MOA at 2850 pfs.

the hornady 75 5.56 super performace does really shoot as claimed at 2940 pfs.

but i can not make it group at all, it just seems to all over the place. at 400 it is all i can do to keep all my shots on the white poster board that put my 12" target on. any ideas?

i do not understand why they perform so very, very different.

My understanding of the Hornady SP is that it's a inhouse blended powder that may or may not be released in canister.

It soulds a lot like RL17 in that high speeds are attainable, but if you check it out groups are harder to come by.

At some point, in my opinion you get past what a bullet can handle speed wise. As you probably know if it don't shoot it won't fly in F/TR no matter what speed the target should be afraid of.

I would shoot what shoots, like they say 100FPS is only a click or two on the sight.

[RWF]

thanks, for the info, it just seemed like there had to be more to it than that. i guess i really was trying to make it a lot harder than it really was.

to me they seemed to very close in wieght and speed.

i would bet money on golf balls at 200 with the 77 BH and with the 75 superperformance i am sure i could not hit a 10# melon with each shoot.

thanks again.

[Powder Finger]

The other thing is even though they are close in weight, those 2 bullets are way different in shape and length.

[Powder Finger]

http://www.accurateshooter.com/forum/index.php/topic,3758615.0.html

[whistlepig]

I have shot lots of both bullets and they do act diff in diff guns. I have found that the 75 gr Hornadys fly better at slower speeds than at the super perfomance load levels. Just my experience. I slightly prefer the 77 Sierra in my setups, but not by much.