AR15 Barrels, best for 55gr?

[2A2Dend]

My current bullet grain varies for 14-16" barrels, in a range from 62gr-77gr otm. I've yet to shoot my latest 11.5" pistol. Strictly guessing, I think it will like the 77gr best.

I've never shot 55gr, but the fact 55gr is more reasonably priced, is my reason for asking. What barrel length/twist/ (brand of barrel) prefers the 55gr best?

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[Caveman Jim]

I believe it really comes down to twist rate not the length of the barrel1-8 & 1-9 twist like 50-62gn bullets and 1-7 like 55-heavier bullets. As far as which barrels (brand)? I would think ALL OF EM will shoot 55gn's just fine.
Someone correct me if I'm wrong.

 

[Certaindeaf]

Just offhand I'd say to use what the military used the longest while using the 55gr. It might not have been the most stable but was a good compromise owing to its observed lethality.

 

[Kruel J]

1:8 seems to be the best compromise. Although I've shot plenty of 55gr through 1:7 and 1:9 without issues.

 

[ron]

You are correct most barrels will shoot 55s well.
All 55s are not equal. Some of the best and some
of the worst groups with different 55s. I like the IMI 55s.
I don't like the Winchester 55 grain fmj bullets.
Basically a 1/9 twist can shoot up to 69 grain bullets.
The 1/9 barrels are a good choice for varmint shooting with
55 grain and lighter varmint bullets. IMHO

 

[Certaindeaf]

wiki

.Early model M16 barrels had a rifling twist of 4 grooves, right hand twist, 1 turn in 14 inches (1:355.6 mm) bore - as it was the same rifling used by the .222 Remington sporting round. This was shown to make the light .223 Remington bullet yaw in flight at long ranges and it was soon replaced. Later models had an improved rifling with 6 grooves, right hand twist, 1 turn in 12 inches (1:304.8 mm) for increased accuracy and was optimized for use with the standard U.S. M193 cartridge..

 

[Medic!]

I thought we just twisted every drop of crap we could out of this subject.

Recommendations for varmit barrel for Colt LE 6920 and BCG

 

[mjbskwim]

I almost always put a 1/8 twist barrel on every build I have done
55gr bullets work great thru it
68?9? grain bullets work great thru it.
I believe 1/9 is good for 45 up to 55gr were as 1/8 is good for most everything (in my experience) and 1/7 ,well I don't think I've had one but it should be for over 60 grains?
I think 1/7 will shoot 55gr fine.......no?

 

[mjbskwim]

I would agree that twist is way more important than barrel length

 

[old11bravo]

Right now, dollar to quality ratio, this is the best bang for your buck. You'll never regret this purchase at this price. $99 while they last!

Ballistic Advantage AR-15 5.56 NATO 16" M4 Barrel - 1/2x28

Barrel CoatingSalt Bath Nitride
Barrel ContourM4
Barrel Length16
Barrel Material4150 Chrome Moly Steel
BrandBallistic Advantage
Caliber Gauge5.56 NATO
Feed RampsM4
Gas Seat Diameter.750
Gas System LengthCarbine
ManufacturerBallistic Advantage
PlatformAr-15
Thread Pattern1/2 X 28
Twist Rate1:7
Weight28 Oz


Ballistic Advantage AR-15 5.56 NATO 16" M4 Barrel - 1/2x28

 

[Certaindeaf]

Right now, dollar to quality ratio, this is the best bang for your buck. You'll never regret this purchase at this price. $99 while they last!

Ballistic Advantage AR-15 5.56 NATO 16" M4 Barrel - 1/2x28

Barrel CoatingSalt Bath Nitride
Barrel ContourM4
Barrel Length16
Barrel Material4150 Chrome Moly Steel
BrandBallistic Advantage
Caliber Gauge5.56 NATO
Feed RampsM4
Gas Seat Diameter.750
Gas System LengthCarbine
ManufacturerBallistic Advantage
PlatformAr-15
Thread Pattern1/2 X 28
Twist Rate1:7
Weight28 Oz


Ballistic Advantage AR-15 5.56 NATO 16" M4 Barrel - 1/2x28

It sounds like the fella has plenty. I think he was wondering about optimal 55gr twist.

 

[Pandaz3]

I usually buy 16" 1/7 twist or 1/8, even though I usually shoot 55 Gr 5.56, a few of my new barrels are chambered for 223 Wylde. I do have a lot of 62 Gr ammo on hand

 

[eldbillbo]

The best accuracy wise using equal quality barrels will be the 1/12 followed by the 1/9.
The 1/7 will do fine though but i have shot all 3 and use 55 grain almost exclusively and see a noticeable difference in barrels of the same brand and quality.

The 1/12 was designed for the lighter grain bullets like the 55 grain then the military switched to heavier 62 grain bullets so they switched to the 1/7 twist barrel. The 1/9 was a compremise between the 1/12 and 1/7 and manufactures have been playing with different twist rates like the 1/8.

I have also had the best results with a .22 conversion kit with the 1/12 twist.

 

[ORYGUNHolsterCompany]

My current bullet grain varies for 14-16" barrels, in a range from 62gr-77gr otm. I've yet to shoot my latest 11.5" pistol. Strictly guessing, I think it will like the 77gr best.

I've never shot 55gr, but the fact 55gr is more reasonably priced, is my reason for asking. What barrel length/twist/ (brand of barrel) prefers the 55gr best?

I think the most important question is usage. What type of accuracy are you needing? Is this for range training at distances under 300 yds? Shooting small targets or varmints? Distance shooting on a budget?

The reason I ask is because basically any functional round / barrel combo that can be had for cheap is generally going to be accurate enough for training and plinking. A 2 moa rifle will still hit 12" targets at 600 yards for instance. 16" Ballistic advantage, PSA, alpha etc. Should do just fine.


For target competition or varmints a little more accuracy will be necessary and may benefit from a less resonating barrel (vanadium is a common element added to the steel for this). At distances 300+yds a heavier bullet will be impacted less by wind. Under 300 yds or so a 40gr "varmint" load will still be quite accurate and very fast, but will suffer exponentially as it slows. This sometimes causes confusion as people think a varmint is small thus the round must be more accurate than a heavier bullet. The shooter often does not consider that the varmint round was optimized for speed at shorter distances, which results in less than optimal performance/ accuracy past its optimized range. This correlates to the accuracy at distance difference seen between 55-68+ gr bullets. This is why the 77 gr are used in the mk12 SPR rifles, to maintain accuracy at further distances.
White oak would be my recommendation if you want a competition accuracy barrel at a great price. I see better velocity from 18-22" generally for barrel lengths and this will be important for long distance repeatability.

Also beware of fluting, dimpling, and all the other flashy crap that usually degrades barrel performance. Looks cool but it's like denting a tuning fork and expecting it to ring the same afterward.

 

[Stomper]

I would agree that twist is way more important than barrel length

I have told all my girlfriends over the years the same thing!

 

[2A2Dend]

I do recall seeing a topic scattered about several other topics that I bounced in and out of.
The past two weeks of my life have been over the top. Sorry for re-hashing.

 

[Boboclown]

The 1/12 was designed for the lighter grain bullets like the 55 grain then the military switched to heavier 62 grain bullets so they switched to the 1/7 twist barrel. The 1/9 was a compremise between the 1/12 and 1/7 and manufactures have been playing with different twist rates like the 1/8.

They switched to 1:7 for tracers, something about designing them for the SAW program and the powers that be deciding that the M16 should use the same ammo. Or so they say, I wasn't at the meeting.

 

[eldbillbo]

They switched to 1:7 for tracers, something about designing them for the SAW program and the powers that be deciding that the M16 should use the same ammo. Or so they say, I wasn't at the meeting.

You are correct that was the original reason. Switching the barrel to better suite the tracers required switching the bullet grain to heavier bullet to match the 1/7 twist.

 

[nwslopoke]

What is the ratio depicting? Say 1/9? Is that bullet spinning 9 times when it leaves the barrel(16"/18") regardless of length or 9 times per inch?

 

[v0lcom13sn0w]

heres my .02... take it for what its worth. i shoot all weights through my 1/7 and 1/8 and dont notice any difference in accuracy with 55gr in either.