Case gauges are not all created equal. Some are closer to the SAAMI maximum spec while others are closer to the minimum spec.

For competition guns which are often chambered tighter, you need a gauge that will catch those rounds that are border line. The Shockbottle 100 round case gauges are designed for competitors and will catch rounds that pass on other gauges.

This round would not go into battery on our STI competition gun. As you can see, it chamber checked on one gauge but failed on the Shockbottle gauge.

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