follow up on the 300-win mag now with a 22-inch barrel 1-10 twist

To determine the optimal bullet weight for a .300 Winchester Magnum with a 1:10 twist rate and a 22-inch barrel, we need to consider the stability factor again while keeping in mind the shorter barrel length, which may affect the achievable muzzle velocity. Here’s a detailed process to identify the suitable bullet:

Bullet Selection Criteria

1. Twist Rate: A 1:10 twist rate is slightly slower than a 1:9 twist rate but still capable of stabilizing a wide range of bullet weights.
2. Caliber: .300 Winchester Magnum (.308 caliber).
3. Barrel Length: A 22-inch barrel is slightly shorter, which may result in slightly lower velocities compared to a longer barrel.
4. Bullet Type: Considering both monolithic and lead core bullets.

Optimal Bullet Weights

For a 1:10 twist rate, bullets in the medium to heavy weight range (e.g., 165 to 200 grains) are typically well-stabilized.

Example Calculation for a 180-Grain Bullet

Using the Miller Stability Formula

Let’s assume a 180-grain lead core bullet with an approximate length of 1.4 inches and a muzzle velocity of 2800 fps.

1. Parameters:
   • Caliber (D): 0.308 inches
   • Twist Rate (t): 10 inches (1 turn in 10 inches)
   • Velocity (v): 2800 fps
   • Bullet Length (L): 1.4 inches
   • Bullet Mass (m): 180 grains
2. Calculating Stability Factor (S):

S=30×(180)2×2800(10)2×1.4×(1+(1.4)2(0.308)2)S = \frac{30 \times (180)^2 \times 2800}{(10)^2 \times 1.4 \times (1 + \frac{(1.4)^2}{(0.308)^2})}S=(10)2×1.4×(1+(0.308)2(1.4)2​)30×(180)2×2800​

Let’s calculate this step-by-step.

Step-by-Step Calculation

L=1.40.308=4.55L = \frac{1.4}{0.308} = 4.55L=0.3081.4​=4.55

S=30×1802×2800100×1.4×(1+4.552)S = \frac{30 \times 180^2 \times 2800}{100 \times 1.4 \times (1 + 4.55^2)}S=100×1.4×(1+4.552)30×1802×2800​

S=30×32400×2800100×1.4×(1+20.7)S = \frac{30 \times 32400 \times 2800}{100 \times 1.4 \times (1 + 20.7)}S=100×1.4×(1+20.7)30×32400×2800​

S=2721600000140×21.7S = \frac{2721600000}{140 \times 21.7}S=140×21.72721600000​

S=27216000003038S = \frac{2721600000}{3038}S=30382721600000​

$S=895996.04$

Finally:

S=27216000003038=1.41S = \frac{2721600000}{3038} = 1.41S=30382721600000​=1.41

With a stability factor (S) of approximately 1.41, 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 .300 Win Mag with a 1:10 twist rate and a 22-inch barrel:

Lead Core Bullets

• Hornady ELD-X 178 grain: Excellent BC and designed for precision at long range.
• Sierra GameKing 180 grain: Proven performance in hunting with good accuracy.

Monolithic Bullets

• Barnes TTSX 180 grain: Solid copper with excellent penetration and weight retention.
• Nosler E-Tip 180 grain: Lead-free, offering good accuracy and terminal performance.

Conclusion

For a .300 Winchester Magnum with a 1:10 twist rate and a 22-inch barrel, bullets in the 165-180 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.