Hi,

New to AR's, and am about 2/3rds done building my first.  It's using a .223 Wylde Hansen Profile barrel by Ballistic Advantage (.223 Rem and 5.56 NATO both work).  The twist ratio is 8:1.  I would like to know which bullet weight is smack dab middle of the road, either the most common for this twist rate or most commonly used?  And should I assume the answer is the same for 5.56 NATO and .223 Rem?

Thanks,
Brian

Anything =62grs...your particular barrel may shoot the heavier projectiles well enough, but the 75s and 77s may not stabilize.

YMMV!

^^ 62 for bulk shooting. 69 match grade.

I am sure you mean 1:8

My Hansen Barrels like 50gr vmax and 69gr smk, sub moa. They will shoot MOA with 75gr bthp, but will group more consistent with the other 2.

It'll chew through 55-69 grains like they're candy, and probably shoot the 62, 64 the best

Looks pretty good for 69 gr Sierra Match King for precision shooting, 55-62 for bulk shooting.  I'm going to pick up a few boxes and experiment ... but first need to read what BA says about breaking in barrels.  I've got the lower (and buffer tube, butt stock) assembled... need to read up a bit and get the thing finished so I can go shooting.  :)   I'll swing by the g-store today and pick up some ammo ...

Thanks,
Brian

I'll pick up some of the v-max too, in 50 gr... thx.

It will stabilize anything that fits in the mag, which means up to the 75gr-77gr loads.

It might not play well with light varmint bullets, which may "explode" in flight (basically shed their jackets).  

Try some Hornady Vmax, Match, and ELD and Federal Gold Medal in weights from 50gr to 77gr.  See what that gun likes.

Thx.... got some fun shooting ahead of me :)

BD

for a 8:1 barrel I think you could stabilize about a 30000 grain round. not sure about how the twist will effect the FPS though that is pretty fast twist.

1 in 8 meaning 1 full twist in 8 inches (50-75 ish), vs 1 full twist in 7 inches(55-77ish grains), vs 1 full twist in 12 inches(40-55ish grains).

All good OP,

C'mon, Babeeee..... let's do the twist!

https://www.youtube.com/watch?v=gdEVW5OMMf0

I think it will stabilize 75gr just fine.

A 1-8 twist will work for anything up to 80 grains.

Now 80 grain bullets will a single load only round

Ballistic Advantage wrote and told me that anything from 50 to 77 grains without any stabilization issues, but that I should experiment (after breaking in the barrel) to find what weight works best.  And for those of us that reload, we know it's more complex than what weight the bullet is.  But for CQC, it's not a big deal.  I picked up some 62 gr FMJ 5.56 NATO yesterday and already have some 55 gr and something in the neighborhood of 70+ gr (can't remember).  I just need an hour to finish up that rifle, and then I'll go shooting....  And I expect the gun will be pretty accurate with the guaranteed sub-MOA barrel from BA, and the Young's Manufacturing national match grade SS bolt:

Part (purchased from):
----------------------------
- Aero Precision Upper/Lower   (Primary Arms)
- Magpul ACS Stock   (Brownells)
- Ballistic Advantage 16" 223 Wylde Mid-gas Hansen-Profile SS Premium Barrel   (Ballistic Advantage)
- Aero Precision Carbine Buffer Kit   (Aero Precision)
- Aero Precision Enhanced B5 Systems Lower Receiver Parts Kit   (Aero Precision)
- Geissele S3G Super 3 Gun Trigger   (Brownells)
- VG6 Precision Epsilon Muzzle Brake, 5.56   (Brownells)
- Young Manufacturing National Match SS BCG   (Young Manufacturing)
- Troy Industries HK Style Folding Battle Sights w/Tritium (Amazon)
- SLR Rifleworks ION 13.7" Hybrid Keymod Handguard   (SLR Rifleworks)
- Aero Precision AR15 Charging Handle   (Aero Precision)
- Aero Precision Mid-Length SS Gas Tube   (Aero Precision)
- AR15 Ejection Port Cover Kit   (Aero Precision)


... No optics yet, just the flip-up HK sites.  I need to research the optics question before I spring for something....


bd

Sample size of 1 with some varied weight ammo going through it:

I have one. It'll shoot under one inch, 5 shot groups with 52grain vmax, IMI 77grain SMK and 75 grain Prvi.

8 twists per inch?
That's nuts

Untrue, 1:8 will easily stabilize the 75 & 77gr OTM bullets. 1:8 is commonly used for the very long 80+ grain VLD OTM types which are far too long to fit in a magazine.

As for the OP's original question, any of the heavier match type bullets in the 69 to 77gr weight range would be what I would try. Every barrel has its own particular preferences so you never know what bullet & load your exact barrel will perform well with. Try some Federal Gold Medal Match and Black Hills loads for example to start with.

This I have 3 1:8 twist barrels I shoot 77gr mk262 variants all the he time shooting very well.  I am not a precision shooter by any means but I can shoot 1MOA no issues if I do my part.

This.

I have an 8 twist LaRue Stealth upper.  I have shot 55g, 62g, 69g, 75g and 77g bullets and it shoots them all very well.

I get 1 moa ALL day long with 77g Federal SMK.

I BA barrel has best results with 68gr Hornady

Stag Arms (http://info.stagarms.com/blog/bid/371861/How-Barrel-Twist-Rate-Affects-Ammunition-Choice) has a nice discussion of twist rates, stability and bullet choices.  

As you get near the limits of the ranges given in the article, it does become less a hard and fast rule than a case of whether or not your particular barrel likes the bullet.  In other words, the article gives a range of 45 to 75 grains for a 1:9 barrel.  Such a barrel should be counted on to handle anything between 50 and 62 grains with no problem.  A 75 grain bullet may or may not perform well from it; some can even go to 77 grains while others cannot.

1:8 will stabilize anything you can get into a magazine.
See what your rifle likes and stock up. Now is the time to do things like this.
55 gr cheap stuff should all be fine as well for training/plinking, but see what your barrel likes best in these too.

Late to the party, but it is bullet length, not weight that determines stability and twist rate.

For instance, a 70 grain lead core jacketed bullet will stabilize fine in a 1:9.  Try that with the all copper and much longer for weight 70 grain Barnes TSX bullet and it will keyhole badly in 1:9.

1:8 will stabilize all known bullets, regardless of construction, capable of being loaded mag length.  Barnes does not make a .224" diameter bullet heavier than 70 grains, so no problem there with its monolithic copper construction.

While there is a argument that you can over stabilize very light bullets with fast twist, the concern is one of bullet construction and velocity,  not weight.  I can stabilize 35 grain Hornady varmint bullets in 1:8 twist at 5.56 velocities.  

On the other hand, some very light constructed bullets fired at very high velocities (well beyond 5.56 velocity) can, indeed, shed the jacket in flight due to excess rpm from the high velocity and literally explode long before reaching the target.  I have experienced this with very light varmint bullets in a 6mm bolt gun fired at over 4,100 fps.  But, that is not going to be the case at 5.56 velocities and light varmint .224" varmint bullets.

Military 62 grain 5.56 tracer ammo is long for weight.  It will not stabilize in 1:9, but will in 1:7, and to my understanding will stabilize fine in 1:8, although I've not personally tried it.  I'm not interested in firing tracer ammo in civilian use, for many reasons.

If you really want to get technical, Burger Bullets has on its website a twist calculator for their own bullets and any other bullets of known BC, based on entering accurate data on velocity and BC (ballistic coefficient).  This data is very reliable.

Bottom line:  Your 1:8 will well-stabilize any ammo that you can cycle through the standard AR15 magazine.  1:8 will even stabilize the 80 grain Berger VLD, but must be single-loaded, as it will be too long to cycle through the magazine.  90 grain single load target bullets will need faster twist, at least 1:7, if not 1:6, but that's another story not applicable here.

I have the exact same barrel and it shot 52 vmax just as good as 77 SMK. Everything in between shoot good too. Handloads are the answer though for squeezing every last bit of accuracy out of it.

Mine are exact same, I get great results from Freedom 69 hpbt remans.

Weirdly enough i get best groups out of my savage 10 1-9 twist with these same projectiles.

Eight turns in one inch, man, that's a fast twist . . .

My BA 1:8 barrel shoots 69 and 77 grain equally well.

This is a tech forum, and some folks are technically dyslexic.

Good observation.  A bullet's weight, length, and construction (materials and construction technique) are integral in picking the right twist.  A larger volume of copper is required to match the same weight of a lead core projectile.  A lighter solid copper projectile may require a higher twist rate.

Another consideration that I never see mentioned in these threads that has a huge influence on bullet stability and therefore, necessary twist rate needed to stabilize a particular bullet,  is altitude.  Nobody ever discusses this aspect, but it makes a really big difference.  I have no problem shooting 77 grain bullets in 1-9 rwist barrels, but I shoot almost exclusively above 3700'.


From an article by Dan Lilja about bullet stability and altitude, using a 243 Winchester with a relatively light bullet as an example:

"If a barrel will be shot only in warm, higher elevation conditions, a 15" twist might be the way to go. If colder, lower elevation shooting is to be done, then maybe a 13" or even a 12" twist would be the best choice".

http://riflebarrels.com/effects-of-altitude-and-temperature-on-rifling-twist/