Case Head Separation

Case head separation occurs when the rear portion of a brass cartridge case detaches from the body during firing, typically leaving the forward section stuck in your chamber. This malfunction creates a dangerous situation where hot gases can escape rearward through the bolt and potentially harm the shooter.

What Causes Case Head Separation

In AR-15s, case head separation typically results from one or more factors:

• Excessive headspace: When your bolt closes with too much gap between the bolt face and barrel extension, the brass stretches beyond its limits
• Over-resized brass: Setting your resize die too low can bump the shoulder back excessively, creating artificial headspace issues
• Repeated reloading: Each firing and resize cycle work-hardens the brass near the case head, eventually causing failure
• Hot loads: Excessive pressure accelerates brass fatigue, particularly in the web area

Why AR-15 Builders Should Care

Unlike bolt action rifles where gases vent safely away, the AR-15’s direct impingement system channels gases directly back toward your face. A separation can send hot gases and brass fragments through the charging handle area, potentially causing injury.

When selecting components on AR15 Outfitters’ builder, proper headspace becomes critical. Quality barrels and bolts from reputable manufacturers typically headspace correctly when assembled, but mixing unknown components increases risk.

Prevention and Detection

Inspect your brass regularly for signs of impending separation:

• Bright rings around the case head indicate stretching
• Use a bent paper clip to feel for thinning inside fired cases
• Monitor primer pocket expansion as an early warning sign

If you experience a separation, stop firing immediately. Remove the stuck case using a broken shell extractor, then have your rifle’s headspace checked by a qualified gunsmith before resuming use.