You can find glued Mil Specs also. It depends on when it was made. They have changed over time.
The reason for the red rather than blue is the blue is made to break free with force. The red requires heat. Since the ejector takes a hit every round, it's best to use the permanent type.
The reason for the red rather than blue is the blue is made to break free with force. The red requires heat. Since the ejector takes a hit every round, it's best to use the permanent type.

funny enough, the US made Springfields are just glued while the Brasillian ones are pinned. I prefer them to be pinned AND glued
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