Quick Answer
To ensure consistent accuracy with handloaded .458 Lott, focus on precise bullet seating, consistent powder charge, and a tight case neck. Use a ballistic calculator to optimize load development, and verify accuracy with a chronograph and target shooting.
Precision Bullet Seating
For the .458 Lott, seating depth is crucial. Aim for a bullet seating depth of 0.010" to 0.020" from the lands, depending on the bullet design. Use a precision seating die or a modified cartridge die to ensure consistent bullet seating. For example, the Hornady SST 500-grain bullet seats well at 0.014" from the lands.
Consistent Powder Charge
To achieve consistent accuracy, use a precise powder measure and load development data from a ballistic calculator. For the .458 Lott, a starting load of 120-130 grains of IMR 4166 or H4831 can produce excellent accuracy. However, it’s essential to verify the optimal powder charge through load development and accuracy testing. A 0.1-grain powder charge variation can result in a 1-2 MOA accuracy difference.
Case Neck Diameter and Tolerance
A tight case neck diameter and controlled headspace are essential for consistent accuracy with the .458 Lott. Use a case trim die to maintain a consistent neck diameter, and check the case headspace before reloading. A headspace tolerance of 0.001" to 0.002" is recommended. Regularly inspect and replace case necks to prevent wear and inconsistent accuracy.
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