3. MEASURE CRACKS IN BARREL SUPPORT ASSEMBLY TUBE.
Measure length of cracks in barrel support assembly tube. If the total length of any crack measures longer than 1 in. (25.4 mm), replace the barrel support assembly. If cracks measure 1 in. (25.4 mm) or less, go to step 4.
4. STOP CRACKS IN BARREL SUPPORT ASSEMBLY TUBE.
Stop drill cracks in barrel support assembly tube at their ends by using a 1/8-in. twist drill.
a. Inspect screw threaded inserts in receiver flange (1) screw holes (2). If receiver flange inserts are loose or damaged, send auto gun receiver to Direct Support Maintenance for repair.
b. Inspect receiver front housing (3) for cracks, distortion, and loose rivets (4). If any of these conditions are found, replace gun.
6. INSPECT BARREL LOCK PIN AND MACHINE KEY.
a. Visually inspect barrel lock pin (5), machine key (6), and headed straight pin (7) for cracks, bends, or other damage. If any of these conditions are found, replace defective part.
b. Check helical spring (8) for proper free length. Helical spring free length should be 1-1/4 in. ± 1/4 in. (31.8 mm ± 6.4 mm). If proper free length is not met, replace helical spring.
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