CONSEQUENCES OF IMPROPER HEADSPACE
Improper headspace may pose safety hazards to the shooter, as well as impair rifle function and performance.
- Excessive headspace may lead to gas leakage around the case or head separation and the sudden release of high pressure gas. A chamber that is over maximum might not show any signs of trouble at all. In fact, you might never know it unless you reload. However, upon firing, the expansion of the case blows the shoulder forward. When you full length resize and set the shoulder back, you will probably set up the excess headspace condition again, potentially causing the stretched brass to eventually crack and break.
- Insufficient or excessively tight headspace may cause malfunctions such as failure to lock. It often makes extraction difficult and may cause dangerous stresses on the mechanism which, in turn, may shorten component life expectancy or lead to failure. If your chamber is below minimum (and thus, too small) you may experience problems with bolt function. The cartridge, being crammed into the excessively tight chamber, pre-stresses the locking lugs of the bolt. After firing, the bolt handle might be hard to lift. Or, in a self-loading rifle, spent cases might not eject far, if at all. The extra force can wear the engagement surfaces of the locking lugs or even wedge the action closed and locked.