Best Bullet Weight For 1 7 Twist Ar15 16 Barrel
The most common barrel twist rates for modern rifles are ratios of 1:7, 1:8 and 1:9. Today the most common rates of rifling in AR-15s are 1:7, 1:8 and 1:9. When Eugene Stoner designed the M16 he originally made things much slower—1 complete turn every 14 inches, with four grooves, to be precise. Ar-15 Rifling Twist Rate. While it is a general rule of thumb with weight, in reality, the longer a bullet is, the heavier it becomes. With newer types of bullets on the market and lead-free designs, some bullets made of copper and zinc are very light but require extra length to achieve the same weight compared to a lead core projectile. 1:7 twist will shoot any .223 / 5.56 bullet up to 77 grains. You can't over stabilize a bullet. If you decide to shoot very thinly jacketed bullets (typically marketed as varmint bullets) weighing less than 55 grains in a 1:7 twist bbl. keep velocity under 2800 fps to prevent tearing the jacket.
Most modern AR-15 barrels will come in three twist rates: 1:9, 1:8, and 1:7. The 1:9 barrel is best for stabilizing lighter and mid-weight bullets between 45 and 77 grains. AR-15 barrels will have the specifications stamped or engraved somewhere on the barrel, like these Windham Weaponry models. (Photo courtesy/Windham Weaponry) As we get faster and faster twist rates - this is becoming more of an issue. I personally know a few guys with 1:7.5 Creedmoors that are having the Hornady Match projectiles spinning their jackets off on them mid-air. Twist rates and bullet weight are often understood, but there are some simple and practical guidelines. I have to feed my SCAR 16 and my SIG 556 Classic Swat (both with a 1-7 twist) 69 gr. or heavier match bullets to get down around 1 MOA. I had my Colt HBAR AR15 (also 1-7) re-barreled with a Krieger 1-8 twist and it does beautifully with anything 55 gr. or over. My Rock River Tactical Entry has a 1-9 twist and it shoots 1 MOA with 55 gr. XM193 ... 55 grain bullets are all I've shot with a few 62 grain M855's thrown into the mix. My groups at 100 yards with the scope at 4x are pathetic. I can do better with my .308 at 300 yards. What bullet weight is popular for accuracy out of my 1:7 twist 16-inch barrel?
The AR-15 can sling rounds out to 500 meters and beyond. But getting that level of accuracy out of the rifle you're (hopefully) building with an 80% lower from scratch means picking the perfect upper - really, the barrel matters most - to finish the build. Whether it's 55-grain .223 Remington or 72-grain 5.65 NATO, barrel length and twist rate will make the difference between MOA accuracy ... For example, the rifling of a barrel with a 1:7 (1/7, 1-7, 1 in 7, etc.) twist rate makes a full revolution every 7 inches. The best twist rate for a given bullet is determined based on the projectile's length, diameter, and weight. When specifically talking about 5.56/.223 ammo, bullet weight is the biggest determiner of what twist rate is ... "Handloading the AR-15 .223 Remington," we offered tips and data for rifles with barrel twist rates of one turn in 12 inches and one turn in 9 inches. Now let's look at rifles with the one-in-7-inch twist. The 7-inch twist is intended primar-ily for heavier bullets ranging from 62 to 80 grains, which it stabilizes very well.
General rule is heavier bullets for faster twist ratio. But each barrel is different.. I have a 1/7 that loves 75/77gr but hates 69gr.. But The other barrel in 1/9 loves the same 69gr. Even the same bullet weight from different mfg can lead to different results.. The Best All-Around Weight of AR-15 Barrel Twist. The M16A2 comes with a 1:7, and the military typically shoot bullet weights from 52 grains up to 77 grains, with 62 grains being the most common in combat. Most experts would agree that the best all-around rate of AR-15 barrel twist would be something in the middle such as a 1:8 or 1:9. I ... I currently own two AR-15s with 1-in-7 twist rates — a 10.3-inch Mk18 Mod. 1 and an 18-inch Mk12 Mod. 1 — both made by Monty LeClair at Centurion Arms. To illustrate how velocity and twist rates can be the ying and the yang of bullet stability and accuracy, I fired a variety of loads side-by-side from the two rifles.
I have a Noveske Recon stainless 16", 1:7 twist. Shooting Black Hills (BH) 77 grain was 1.3 MOA Shooting BH 55 grain was ~2 MOA My Noveske Light (M249 barrel w 1:7 twist) was slightly larger MOA. My LWRCI M6A3 1:7 shooting 55 grain BH was 3-4 MOA My Rock River Chrome Moly was about 1 MOA w Black Hill 55 Gr. This was all with the same Nightforce ... If you're going to buy an AR-15 chambered in 5.56mm NATO, it's hard to go wrong with either a 1:7 or 1:8 twist barrel for standard shooting. Those will handle a wide range of bullets safely. Barrel Twist How many "inches per turn" is your rate of rifling twist. This number is used along with other inputs to determine the stability and related trajectory metrics. Typical value for this input is between 1:7" and 1:13".
For example, let's consider the same 45 caliber rifle with a 1 in 18″ twist rate. At a muzzle velocity of 1,000 feet per second (fps), the bullet is spinning at 666.67 revolutions per second (rps) or 40,000 revolutions per minute (rpm). At a muzzle velocity of 2,000 fps, that same bullet will be spinning at 1333.3 rps or 80,000 rpm. What grain bullet is best for a 1:7 twist barrel? :?: After a long absence, I want to get back into EIC and service rifle competition. I have a Colt Sporter Match Heavy Barrel in 5.56 mm of course, and according to what I remember it is a 1:7 twist barrel. Most AR-15 upper 300 Blackout rifles feature the 1:7 and 1:8 twist rate, which is the rifle barrel's spin rate. We refer to it as one rotation over a particular inch of barrel. With a 1-7 twist rate, for instance, it means that the bullet will be spun once over 7 inches of rifling. That's 8 inches of barrel for the 300 BLK 1-8.