Being new to reloading .223 rem, please educate me on bullet weight and twist rate. I have two rifles for which I will be reloading – a 1/7 and a 1/9 twist, both are semi-auto.
For starters, I’ve been told various and often conflicting things from well meaning individuals. For instance:

1. “Bullet weight doesn’t matter, it’s all about bullet shape – the longer the bullet the faster twist you needâ€.
2. “Bullet shape doesn’t matter – heavy bullets are for fast twistâ€.
3. “Put a bullet under 60 grains in that 1/7 and it’ll fly apart in flightâ€.
4. “Put a bullet over 60 grains in that 1/9 and it’ll just tumble all overâ€.
5. “ You can shoot all weights and shapes regardless of twist rate – just some will be more accurate than others.
And my personal favorite – “what’s a twist rate, never heard of it. I just throw some powder and some lead together and let er’ ripâ€.


Anyway, as you can see, not everything you are told is helpful. My goal is to work up a accurate loads for each rifle. As opposed to just starting someplace, I thought I’d check with those who have experience and maybe learn something constructive. If you have thoughts about correct twist vs. bullet weight/shape please let me know.

Thanks in advance.

Vlad

Lots of info on bullets and rifleing twist here.

http://stevespages.com/page8e.htm

Here is a little more info:

http://sst.benchrest.com/shilentwist.html

Vald,

Proper twist rate is a factor of bullet length and velocity. The higher velocity and faster the twist, the higher the revolutions per minute of the bullet, which is where the bullet “flying apart†comes in. I have heard this will happen when shooting .224 bullets made from 22 RF brass, but have never experienced it myself. I don’t believe the 223 round will shoot a bullet fast enough to do this, but I suppose it’s possible under the right circumstances. Shooting at 220 Swift or 22-250 velocities is a different story.

Instability at low velocity with standard bullets is why some suppressor manufacturers won’t warranty their 223 suppressors (for AR/M16 rifles) if they are used with subsonic ammo. The standard bullet weights at velocities below 1,150 FPS may not stabilize and damage the suppressor. I have shot 125-130 gr. bullets out of my Colt at subsonic velocities with no stability problems, at least at short range. Again generally speaking, the longer the bullet, the shorter the twist required.

I have read information from those that know better than I, that you can’t over stabilize a bullet, but you can under stabilize one, which is, as I understand it, why Colt went with the 1/7 twist after the military changed to the longer, heavier ss109 bullets. The shorter twist rate wouldn’t stabilize the longer bullet, but would still stabilize the old lighter, shorter M193 bullets.

I have a Colt H-Bar with a one in 7 twist. It will shoot 50-55 gr. Bullets ok (for some), but with a 69 gr. Sierra, it will shoot less than 3/8†groups if driven fast enough. Bullets in the 68 to 80 gr. range are best suited for the 1/7 twist, as can be determined by the notes on boxes of bullets of various manufacturers.

Bottom line: shoot longer bullets in both rifles, though the 1/9 twist may not work so well with the longest of bullets.

Good luck. Hope this helps.

David

I bought some Federal Gold Medal match loads with Sierra 77 grain bullets for a 223 with a 1:12 twist. Those bullets keyhole every time even at 25 yards. On the other hand, the gun shoots Speer 70 grain Semi-Spitzers very well. The Speer is obviously a shorter bullet which is probably the reason it does so well.