Took my Uberti '51 Navy to the range today to test out a new R&D conversion cylinder. Shooting 38 Long Colt with 3 gr. of Unique and a 148 gr. hbwc. About 20 rounds and almost all keyholed. What causes that? Velocity too low to stabilize the bullet? What is the solution? A heavier load? Switching to black? Its a new problem to me. Thanks