I am looking at an ar-15 but I am having a hard time to decide what is the right rate of twist for using 50 to 55 Gr. ballistic tip ammo. The options I have are 1:8 or 1:9 what would be the best for my situation?
Thanks in advance,
_Righty_

I had a 16" Varmint Rock River Upper with a 1:8 twist and it shot everything I put in it very well. It shot Black Hills 52gr HPs very nicely, it would also put 60gr Nosler Partitions in a very tight group as well.

Theoptimum rate of twist for .223 bullets in the 50 to 55 grain weight range is probably a 1:14; no faster than a 1:12. However, 8" and 9" twist guns have provided good accuracy in many instances with light bullets. The main thing to remember about twist is that if you have too much, you very well may still be OK. If you don't have enough, however, you are absolutely out of luck. No exceptions.

The 9" twist will usually stabilize bullets up through the 75 Hornady A-Max. It is considered by many to be the most versatile of the AR-15 barrel twists. For the 77 and 80 VLD's you need at least an 8" twist.

I actually prefer 1:12 twist in my 223s for shooting light bullets. But the 1:8I had in my Rock River shoot everything very nicely. Now the 1:9 that my Mini14 has...........I don't think a guy can blame the twist for being innaccurate in that case

I have a RRA with a 1in8 24'' EOPand it will put 3 50 gr blk hills remanufactured .223 ammo in one ragged hole at 100 yds. It shoots anythingI feed it well. What is nice about the tight twist is you can shoot 68 or 69 gr bullets awesome plus the lighter 50-55 gr ones too, where you can't get a heavy bullet to shoot accurately in a slow twist bbl.

1:9 is the most common twist rate put on factory ARs. I wouldn't bother spending more on a faster twist barrel unless you are planning on handloading for it using VLDs or you are buying a specialized varminter gun. Most of the bulk (cheap) .223 ammo is going to be in the 55gr range anyhow.
FWIW, my 1:9 Bushmaster HBAR seems to shoot everything well across the board in factory ammo.

The best highpower shooter that I personally know uses kriegers in 1:7. How he explained it to me is that a 1:8 will stabilize a VLD very well in a bolt gun because of the extra bit of velocity a bolt gun offers and ok in an AR, but further downrange the 1:7 in an AR makes a difference. I don't know if what he says holds true or not, but I can't shoot well enough to tell the difference like he can.

Missed something along the way... what is a VLD?

Aha! Would not have thought of that all day.

Has anyone tried the Hornady 75 Grain TAP FPD out, and does it expand violently like a varmint round?