When you load your mags, smack the back side of the full mag against the heel of your other hand to set all rounds completely to the rear of the magazine. There is very little clearance front to back for the .45ACP rounds in these mags, and the tip of the bullet may be in contact with the front wall of the mag, which can cause problems. I typically perform this action on any pistol mag I load, but it's important to do so with the .45 Shield. Compare the S&B to other ammo you may have. It may be very slightly longer in OAL.

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So long ... Ken