1/9 twist what weight bullets?

J

jimmyg75

New member
Just got my new upper it is a .223 1/9 twist, broke it in with 2 boxes of real cheap winchester ammo. Now I would like to see what this upper will do for groups, This is my only 1/9 twist rifle so I was looking for some suggestions on where to start in reference to bullet weight and brands, I do not reload so it has to be factory ammo maybe your opinions can save me a little time and money. Thanks oh yeah it is a REDXARMS 16" ss bull barrel.

Jim G.
 
The cheam umc 45gr hp stuff doesnt shoot too bad. Iv seen it for 10-12$ a box. If u wanna spend the money the v max do shoot great. My buddies red x shoots the 40's great along with hornady 55gr Soft points.
 
As the old rule of thumb
This is not a perfect thing, there are so many things that can change. But, you ask for suggestions. Here is where I start.

These figures are based on 3000 FPS

1:12 twist will go about 180,000 RPM so it will require a bullet from 42 to 55 GR. 48 grains is an average. this is a good bullet weight to start out with.

1:9 240,000 rpm will reguire a bullet 55 to 72 average 63 gr.

1:8 270,000 rpm - bullet from 60 to 78 average 67 gr

1:7 308,000 rpm - bullet from 62 to 85 average 70 gr

Again," this is what I would start with. Remember all guns and barrels are different. And you need to find the load that fits your gun.
 
I like either the 50 vmax by Fiochi or the 52 grain hp by Ultramax. Less then 50 cents a round and my rifle shoots either well.
 
my 1/9 twist shoots stuff from 55gr and up in a 1" group. the 40gr stuff is about a 2.5" group. I hunt with 55gr Vmax, and have used 62gr Vmax with very good results.
 
Jldoll hit on it, but here is the rest of the story.

MV * 720 / twist = RPM.

Hornady Vmax & SP's both have a RPM limit of 290,000 RPM
SXSP & TNT's(low vel) & Dogtowns(from 2 years ago) have a RPM limit of 240,000 RPM
So choose bullet weight, or velocity accordingly.

MOST 9-twist barrels will stabilize a 70gr bullet. The SMK was designed for a 9-twist. MOST barrels(regardless of maker) will vary twist by about 1/2 a twist. So YMMV.
 
Thanks for all the suggestions guys I am going to pick up a bunch of diff ammo today. I will let you know what worked for me.

Jim G.
 
Darkker
Your right on, The forumla I use is.

MV X 12" = [answer] Divided by twist. Take that answer X 60 minutes = RPM

The answer is the same. If everyone started out using these forumula's They could save a lot of money on ammo
 
I have a Savage 223 that just loves 65gr. sierra's, and doesn't shoot the 40gr. very well. You might give them a try with some AA2520 and they'll do about 3000fps without pressure sign's

Steve
 
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