My goal is to build the most accurate gun possable with in my buget.I know I want A 24 inch bull barrel .What I want to know is what twist rate I will need to get the best accuarcy?I will mostly be shooting just paper from 100 to 600 yds.I will also be useing box amo till about the first of next year at witch time I will hopfuly start reloading.Also is there a certian bullet weight I should use? I was told by some people not to get stainless steel why?I know that I should look for a non-crome lined barrel.If there's anything I left out please let me know.

The rate of twist depends on the bullet weight you will be firing. I have a 1:12 barrel and becasue of this all my bullets are 55gr. The higher in bullet weight you go the tighter the twist will [have to] be. the most common is 1:9 (I think) and this will allow you to shoot a number of different weights, but to answer your questions of what is the most accurate twist will be, I would need to know what bullet weights you will be firing.

Tropic

Tropics got it pretty close.  The stabilization is also effected by the bearing surface and where it lies with respect to center of mass of the bullet.  There are heavy VLD ( Very Low Drag) bullets that require a slower twist than normal ojive bullets of the same weight.  This is because the bearing surface is nearer the back with a long slender ojive (nose).

For longer ranges you will want to shoot heavier bullets.  Actually you will want to shoot bullets with the highest Ballistic Coefficient (BC) you can, but weight, or more accurately Mass, is a large component of the variables that affect BC.

Ballistics 101.  Bullets with higher BCs fly farther with less rapid scrubbing off of velocity (slower deceleration)than bullets of lower BCs.

Visit here for some of the highest BC for conventional bullets. [url]http://www.bergerbullets.com/catalog.htm[/url]

I am going to be target shooting  paper targets at 100-600 .I wll be buying only box ammo off the net till after the first of next year .Then I will start reloadig.I want to build an AR that will give me the best accuarcy.I know I will buy a new RRA N/M complete lower but I stiil have'nt decided on a upper or barrel.Before I buy a barrel I want to know what twist rate I should buy to acheve my goal.I will select a bullet weight after I get my barrel.    


Tropic my bullet weight will be what ever is the most  accuarte at the range I'm shooting.

What I want to know is what twist rate is the most accuarte in a 24 inch AR barrel  useing box ammo.I can buy diffrent ammo to find the best bullet weight .I will probably only be able to buy one barrel.

What Tropic and I are trying to say is different bullets will shoot at their highest accuracy potential out of different twist rates.  You can buy all kinds of different weight bullets in factory loaded ammo.

Edited to add; I would select a weight range, say 62 to 75 or 80 grain bullets and a common type of ammo that is readily availible out of a box, say like Black Hills Match.  They use the Sierra LTB type ojive. Based on that the 1:7 twist rate will work better.  69 down to 62 gains Sierra bullets will do better out of a 1:8 twist.  Kreieger makes a 1:7.75 that is a pretty good tweener.

Thankyou :half cocked and tropic I'm not trying to be a smart tail I'm just not convaing my message right. What I mean is shooting mostly paper with box ammo at 100 to 600 yds what twist rate and bullet weight will do the best.
(Example lets say a 10x1 will shoot 55gr match bullets in 3/4 inch groups at 100 yds and 7 inch groups at 600yds .A 8x1 twist with 65 gr bullets will shoot 1/2 inch groups at 100yds and 4 inch groups at 600 yds .then 8x1 is the on I would want.  I want to know what twist will give me the best results.

If you're limited to out of the box ammo most accross the course match shooters shoot 69 grain Sierras at 200 and 300 yards and the 80 grainers at 600.  80 grain bullets might not fit into your mags and may have to be loaded 1 at a time through the ejection port. Some shoot the Sierra 73s, 75s and I think there is a 78 grain now, that all fit in a magazine.  Federal (Gold Medal Match) and Black Hills both load ammo with some or all  of these bullets.  Given that I would go with that 1:7.75" or 1:8".

55 grains will have a hard time at 600 yards.

If I recall correctly, heavy bullet box ammo is limited to 69 grain match (Federal?) and 77 grain Black hills ammo.

You can reload this stuff very cheap, while you are looking at a buck a bang with factory stuff.

A standard barrel for highpower shooters is the 20" 1/8 twist.  This can handle anything up to 80 grains and 600 yards plus.  

The 77 grain loads are loaded to magazine length, while the 80 grain bullets are about 1/4" longer than standard.  These are single loaded into the rifle due to the obsolete weird rules of highpower shooting.  

2-gun.  I'm not that experienced with Bullet Drag Coefficient or anything but would like to suggest to you that you begin reloading immediately if you plan on shooting precision.  Expect to pay big bucks for match grade black hills stuff when you could get started reloading for the price of a small number of those boxes of ammo.  You'll eventually get better accuracy and it's much more satisfying knowing you made the ammo that hit the center of your target.

Actualy it's a law of physics, similar to that one about 5 lbs. of shit in a 3 lb. sack.

82nd is on the right track here.  You'll save (*) money in the long run plus be able to try more alternatives if you get into reloading now.

*  If I were to add up all the time and money I have into reloading I would probably be better off and further ahead if I got a second job at McDonalds and used that money to buy match ammo.  But it keeps me out of the bars.

Dont want to throw another variable into the works but isn't a 24" barrel too long for a 5.56mm bullet? Me thinks that a 20" would allow 90% of all the gasses to burn off before the bullet leaves the barrel. (trying to remember stuff that I forgot long ago)
Won't the exta 4" slow the bullet by a few FPS if the gasses are all burned off before the projectile leaves the barrel?

Tropic

I thank all who responded.I have taken in all info and now I Think I want a 8x1 twist :) BUT now I am conserned as to lenght .Should I go for the 24 inch to acheive my goal or 22 inch or 20? I thought the lenght did'nt slow modern powder down.I know in black powder too lond a barrel will hurt accuarcy  as it is less powerful but I did'nt think it afected moderen powder.

Of the 20,22,and 24 which is the most accuarte at 100-600?

I plan to get a lee press and dies after the first of the year but for now I'll be buying  box amo. I will be shooting mostly just 100-300 but I will shoot out to 600yds on ocasion.

As for length, again, it comes back to reloading.  You can buy different burn rates for your propellant and maximize the 24".  Accuracy, per se, is not affected by barrel length.  Velocity deviations will become more evident, however, at longer ranges in the form of greater verticle dispersion.

Edited to add; Get the 24".

So to be clear to obtain the best accuarcy with box ammo you recomend  a 24 inch with a 7.75x1 or 8x1 twist weight?