What kind of ammo was being used, new or reloads? I have found that if I have my thumb positioned incorrectly on a couple of my 1911a1's, the slide will lock when firing. Try to load 5 rounds, and please check your thumb position after each shot.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
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