Twist Rate and Bullet weights

[Strawberry780]

First I'd like to say yes I search this form and could not find the answer to my question........

Having said that, I have a Savage model 12 in .223 with a 1:9 twist barrel.

I have done some "long range" (660 yds long for me) with 80 and 90 grain bullets.
Yes I know with the twist rate I can shoot the larger .223's. and it's a blast.

What about the smaller bullets say 55 grain bulk ammo or varmint 32 grain stuff? Would it be too much spin?

thoughts.....

thanks

 

[glockgrouptherapy]

Ive heard somewhere that a really fast twist will spin bullets so fast they will blow apart after leaving the barrel so in your case don't spin anything lower than 45gr varmint rounds. most AR-15type rifles have a 1-9 twist. I have several ARs and push 55s through them all the time and no problems. so you should be fine. word of caution tho, in my custom build AR with a 16in 1-9twist, it will make MOA at 300 with 60-77gr bullets, but the 55s I put through it were all over the place. even at a 100 yds I was spreading up to 3inchs. and those were a mix of federal XM193bulk and hand loads.
hope this helps

 

[BadAsMo]

I doubt you will blow up bullets with a 1:9 twist with 223 velocities.
1:9 is not fast enough to shoot anything heavier than about 75 grainers safely.

 

[glockgrouptherapy]

http://thefiringline.com/forums/showthread.php?t=477488

this will explain what happens with varying twists rates.

 

[xdmer]

http://thefiringline.com/forums/showthread.php?t=477488

this will explain what happens with varying twists rates.

Thanks.

 

[Strawberry780]

thanks as well

 

[silverfoxdj]

Gracias great info

 

[Magellann]

That has some good info to read.

 

[pmatuk]

here is a berger calculator http://www.bergerbullets.com/litz/TwistRuleAlt.php

 

[silverfoxdj]

here is a berger calculator http://www.bergerbullets.com/litz/TwistRuleAlt.php

Thanks I'll use it..

 

[langbanger]

My 700 tactical 223 9" twist shoots 55 grain hornady z max quite well, it also loves 55 gr sierra gamekings, but really shines with 70 gr Berger match vld.

 

[Boomer454]

here is a berger calculator http://www.bergerbullets.com/litz/TwistRuleAlt.php

This is interesting, but I have a question.

I put in my bullet. A 70 grain Berger, at 2700 fps and came up with 30.08
For stability. Is that good? How much is too much.

 

[glockgrouptherapy]

if I remember correctly the higher the stability number the better, but like in that link I posted on the first page there is such thing as over stabilization. to paraphrase, the bullet will not nose down as it should and more or less "land like a plane", the other bit is that it will not follow the standard arc path and deviate more erratically.

I don't know if this plays any part in calculating but try changing the ballistic scale from G1 to G7. G1 was designed when bullets were flat based such as a berger 60gr varmint, where as G7 is for Boat tail rounds. Something I found out made a huge difference when I tried my had at long range the first time.

 

[Boomer454]

I made a bit of a mistake with my numbers. I put in 224 instead of .224...
Oops! The proper numbers being it down to 1.55 and that sounds about right.

 

[Canadian Dad]

I have done some "long range" (660 yds long for me) with 80 and 90 grain bullets.

Do you mind if I ask what kind of load with these? I have found that I can only get a max load of 25.5 grains of Varget with 68 grain Hornady A max and 25 grains with the 75 grain A max. I am using the same rifle. Great velocities with no signs of overpressure.

 

[Strawberry780]

I am loading 22.9 gr of Varget and the CAOL is so that the bullets are just off the lands. THe end result is that i have to use a single feed ramp as the bullets are too large for the mag