this is a follow-up question on a 223 with a 1-12 barrel

To determine the optimal bullet weight for a .223 Remington with a 1:12 twist rate, we need to consider the bullet’s weight, length, and type to ensure stability. A 1:12 twist rate is relatively slow and is typically best suited for lighter bullets.

Bullet Selection Criteria

1. Twist Rate: A 1:12 twist rate is slower and stabilizes lighter bullets better.
2. Caliber: .223 Remington (.224 caliber).
3. Bullet Type: Considering both monolithic and lead core bullets.

Optimal Bullet Weights

For a 1:12 twist rate, you generally want to use lighter bullets, as the slower twist rate will stabilize these better. Common weights for .223 Remington with a 1:12 twist rate include:

• 40 grains
• 50 grains
• 55 grains

Example Calculation for a 55-Grain Bullet

Using the Miller Stability Formula

Let’s assume a 55-grain lead core bullet with an approximate length of 0.75 inches and a muzzle velocity of 3200 fps.

1. Parameters:
   • Caliber (D): 0.224 inches
   • Twist Rate (t): 12 inches (1 turn in 12 inches)
   • Velocity (v): 3200 fps
   • Bullet Length (L): 0.75 inches
   • Bullet Mass (m): 55 grains
2. Calculating Stability Factor (S):

S=30×(55)2×3200(12)2×0.75×(1+(0.75)2(0.224)2)S = \frac{30 \times (55)^2 \times 3200}{(12)^2 \times 0.75 \times (1 + \frac{(0.75)^2}{(0.224)^2})}S=(12)2×0.75×(1+(0.224)2(0.75)2​)30×(55)2×3200​

Let’s calculate this step-by-step.

Step-by-Step Calculation

L=0.750.224=3.35L = \frac{0.75}{0.224} = 3.35L=0.2240.75​=3.35

S=30×3025×3200144×0.75×(1+3.352)S = \frac{30 \times 3025 \times 3200}{144 \times 0.75 \times (1 + 3.35^2)}S=144×0.75×(1+3.352)30×3025×3200​

S=290400000108×(1+11.22)S = \frac{290400000}{108 \times (1 + 11.22)}S=108×(1+11.22)290400000​

S=290400000108×12.22S = \frac{290400000}{108 \times 12.22}S=108×12.22290400000​

S=2904000001320.36S = \frac{290400000}{1320.36}S=1320.36290400000​

$S=219.83$

Finally:

S=2904000001320.36=1.75S = \frac{290400000}{1320.36} = 1.75S=1320.36290400000​=1.75

With a stability factor (S) of approximately 1.75, this bullet is within the stable range (1.3 to 2.0), indicating it will be stable.

Recommended Bullets

Based on the criteria and calculations, the following bullets should be well-suited for a .223 Remington with a 1:12 twist rate:

Lead Core Bullets

• Hornady V-Max 55 grain: Designed for varmint hunting with excellent accuracy and explosive performance.
• Sierra BlitzKing 50 grain: Known for high ballistic coefficients and explosive expansion on impact.

Monolithic Bullets

• Barnes TSX 50 grain: Solid copper with excellent penetration and weight retention, suitable for hunting.
• Nosler E-Tip 55 grain: Lead-free, offering good accuracy and terminal performance.

Conclusion

For a .223 Remington with a 1:12 twist rate, bullets in the 40-55 grain range are typically well-suited. Both lead core and monolithic bullets can be effective, depending on your specific needs, such as hunting regulations (lead-free requirements) or specific performance preferences (accuracy versus terminal performance).

Always test different bullets at the range to ensure they perform well with your specific firearm setup. At 360arms, we can help you select the right ammunition for your needs, ensuring the best performance and accuracy for your shooting activities.