Am starting to educate myself on selecting parts for an AR for my son.
Trying to go for long distance accuracy.
Looking into buffer systems/gas management .systems info.
Is the Geissele braided springs or Sprinco springs good ?
Good barrel options and gas tubes also.BARREL OPTIONS, COMPLETE OR BUILD ?
FYI we are starting with the SanTan TacticalSTT15 upper and the Radian AX556 lower and TRIGGERTECH B.A.D. Edition.
Black hole weaponry poligonal barrel chronograph faster for me than normal rifling. To get the maximum velocity out of a 223 you will need 26” or so of barrel. Whiteoak used to sell such a long barrel. I like the flat wire springs like Tubbs/Strike Ind better than most. A well fit free float handguard with bipod or bags would be quite helpful. Building it yourself, lube and torque the barrel nut on, this is done in steps. Assure the muzzle crown is square to the bore. I also use a 308 size muzzle device if I use one at all. The next step is highly consistent ammo. You may end up weighing each casing, powder charge and bullet. There is much to accuracy. It seems to me, the smaller the bullet the bigger effect changes in process incur.
Thanks for the info.
I have watched the videos of the process of installing the barrel.
What kind of difference does the poly rifling make for you ?
About 10% faster than my 5R Satern. Both 16” 300BLK same everything.
I have been trying to navigate the BHW site but says it is under construction.
Might just end up with the White Oak Armament heavy barrel.
My thought, in all the reading shows a drop off after about 20" barrel. Barrel Length, Trajectory, and Learning Your Zero - Everyday Marksman
223 Remington/ 5.56mm NATO barrel length and velocity: 26 inches to 6 inches – rifleshooter.com
Here is another thought. How much does the bullet velocity change during dwell.
What is the effect of barrel length after the gas block.
Right now I am torn between 20"or22". The 24" (from the graph seems to be a flat line between the 20"… There looks to be a loss after20" to 22".
I am leaning to the 20" barrel.
My understanding is the work done on the articles is from bolt action barrels.
I usually purchase my BHW barrels from SurplusAmmo. They have a variety that is not available elsewhere. The BHW company merged and have a new website: BHW Redirect – Black Hole Weaponry their outlet: https://truesportingarmsllc.com/ sometimes has great deals on overruns.
I did a bit of research, a 5.56 26” barrel has an equivalent velocity to a 223Valkyrie with a 20. Of course with the longer barrel a lighter bullet would be in order. There is a balance to bullet weight and barrel length per cartridge for maximum muzzle energy. If you were preferring heavier bullets in the range for 5.56 you will find shorter barrels will maximize the velocity. 24” would work well with 70gr where 55gr will increase in velocity up to 27”.
Any recommendations as to twist rate for 55/62gr ?
1:9, 1:10 ?
I use this calculator:
https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
The bullet length is as important as the weight. I use a lot of machined copper bullets. They are longer than their lead counterparts. Changing the length and weight you can see how the stability changes in the calculator.
How is that for a non-answer?
I’m a fan of ARP barrels. He leans toward the 6.8 spc and wildcats but he makes some great .223 wylde barrels as well. Check the website often as he adds stock regularly to keep from being overrun with orders.
Thanks for the research info. I have plugged in several numbers and been amazed.
Local gunsmith suggested the 1:10 for the 55gr. So now I am on a quest.
More info. GREAT have checked that site and will do more follow up !!!
Length of barrel affects velocity, trajectory but not accuracy. Quality of barrel more likely to affect that.
1:7 or 1:8 if you plan on shooting 62+ gr bullets
Truing or “lapping” the upper receiver face is an important and often missed step in an accuracy build.
Quality optics
Solid optic mount that cantilevers off receiver
Consistent ammo. If you don’ have a chronograph or radar get one. The best gun in the world will only be so so if it doesn’t like the ammo. Get your SD’s down to low single digits. A slower bullet with a lower SD will group better then a faster bullet with a higher SD all other things being equal, but higher velocity does help in other areas, like wind drift and ranging.
Just my opinion.
Albroswift, Mic, and MrMachinist, THANK you guys for the feedback 
.
Using that calculator that was the NON ANSWER I came up with an “in stock” item at WHITE OAK ARMARMENT.
20" predator (semi bull)
416R
1:12
Rifle gas length
low profile gas block
Fitted BCG
I shoot 55 and 62 gr so I feel ok with the twist.
TO you and yours a BLESSED holiday season !!!
Here is the Sg JBM - Calculations - Stability
1.356 figured that was good enough.
Now, instead of fanaticizing about 17WSM I might have to get into loading some 45gr 5.56.
A couple of links I found very informative…The Best AR-15 Barrel Length and Twist Rate by Caliber - Gun Builders Depothttps://www.ammoman.com/blog/5-56-twist-rate-
I’ve seen twist rate charts that disagree but 1:12 will not be a good match for any AR bullet >36gr. Even .308 AR’s run 1:10. But fortunately, when you see keyholes and 6" groups on your 200 yard targets it’s easy to change barrels on an AR platform. 
Mic, with all the help I have received from ALL on this topic. I have come to settle on a build that looks like this.
LOWER
Radian ADAC lower
VLTOR A5 buffer set W/ Odin adjustable weight (5.8 oz.) and Geissele 42 spring
TriggerTech BAD Edition Adjustable trigger
ERGO SUREGRIP pistol grip
The “finished working” model.
UPPER
SANTAN w/forward assist
WILSON COMBAT 20" .223WYLDE 1:8 416R fluted SUPER SNIPPER, threaded
WILSON COMBAT Nickel Boron BCG
WILSON COMBAT Gas block/tube.
AT3 M-LOK 15: hand guard.
Completed this build 45 minutes Ago.
My AR-15 has a 1:8 twist. Most of my .223 is 55gr. My 5.56 is 65gr.
Is this an issue? Thanks.
Not really - just buy XXXL targets 
just kidding - kinda have to define what “long” distance means for you. Longest at my range(s) is 400 yd. Many posts I see on FB are 500+ yds out to 1k and beyond (maybe those a XL long distance for sure.)
Also, run some AR 15 ammo through your fav ballistic calc. From what I recall, the “battlefield zero” is about 8 inches out to 300 yds. Aim for center mass and expect results.
And remember, my credentials are only good on TV and soap boxes.
My AR-15 is for distances between 25 and 100 yards. I have a red dot with a flip up 3x multiplier behind it. No scope. I consider 100 yards to be “long distance”. Lol
So given that, I imagine not a lot of issues with a 1:8 twist?
Did you read the link in my reply above about “Best AR15 Barrel Length and Twist Rate” ?
Scroll down that article until you see the charts that explain the numbers you get from the calculator above .
The values I get from info you gave gives a Sg of 1.956(figuring bullet length of .91" and velocity of 3100 fps) which is a 1.956. So that is at the upper end of the 1.5 to 2.0. which is " Stable and long range".
Read that link to see all "levels of Sg catagories.
