Here is a few pics that may help........
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Standard AR fire control pocket, cannot accomodate sear without machining
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USGI sear installed in M16 receiver
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Factory sear block installed, this should look similar to yours inside.
[Broken External Image]
Standard AR fire control pocket, cannot accomodate sear without machining
[Broken External Image]
USGI sear installed in M16 receiver
[Broken External Image]
Factory sear block installed, this should look similar to yours inside.