What Is Strike Depth and How Do I Measure It?
Strike depth is the indent left by the firing pin on the cartridge rim. That indent is the point at which the primer is activated. ELEY publishes an ideal strike depth for its cartridges of 0.012-0.015 in, and it is measured with a strike depth gauge.
It is the single most useful measurement a rimfire shooter can take from their own rifle, because it verifies directly that the rifle is delivering the energy an ELEY cartridge is designed to receive.
Why a Minimum Strike Depth Exists
A .22LR cartridge carries its priming compound inside the folded rim of the case. Firing the rifle drives the firing pin into that rim, crushing it against the edge of the chamber and detonating the compound, which in turn ignites the propellant.
A minimum strike depth is necessary to transmit sufficient energy to the primer to cause ignition and ensure the cartridge does not misfire. ELEY’s published window of 0.012-0.015 in is the depth range at which an ELEY cartridge receives the energy it was engineered around, and it is universal across the .22LR range. The same figure applies to ELEY tenex, ELEY match, ELEY team, ELEY club and ELEY sport.
How to Measure Strike Depth
A strike depth gauge is a small, inexpensive tool that sits in the chamber in place of a cartridge and records the indent the firing pin leaves in it.
- Make the rifle safe. Confirm it is unloaded and the chamber and magazine are clear.
- Insert the gauge into the chamber where a cartridge would sit.
- Close the action normally and release the firing pin as you would when firing.
- Remove the gauge and read the depth of the indent.
- Compare the reading with ELEY’s published 0.012-0.015 in.
- Repeat several times. Consistency between strikes matters as much as the absolute number, because variation in the energy delivered to the primer becomes variation on the target.
What the Reading Tells You
| Reading | What it indicates | Practical step |
|---|---|---|
| 0.012-0.015 in, repeatable | The rifle is delivering strike energy to ELEY’s published specification | Move on to matching the batch to the barrel |
| Below 0.012 in | The firing pin is not reaching the depth ELEY specifies | Strip, degrease and relubricate the bolt, inspect the firing pin tip and spring, then re-measure |
| Varying between strikes | Something is damping or obstructing firing pin travel | Clean the bolt thoroughly and re-measure; check headspace against ELEY’s 0.040-0.041 in |
Strike depth has a partner specification. ELEY’s recommended headspace is 0.040-0.041 in, the clearance that holds the cartridge rim in a repeatable position between the barrel and the bolt face. Headspace is one of the conditions that produces the strike depth reading, which is why the two are checked together.
Both are worth re-measuring over the life of a rifle rather than once. Firing pin springs weaken over thousands of rounds, firing pin tips wear, and old lubricant thickens inside the bolt and damps pin travel. That is what a hard-working target rifle does rather than a defect, but it does mean the gauge should come out periodically, and always after bolt work.
The Bottom Line
Strike depth is the indent the firing pin leaves in the cartridge rim, and it is the point at which the primer is activated. A minimum depth is necessary to transmit sufficient energy to cause ignition. ELEY’s published ideal is 0.012-0.015 in, measured with a strike depth gauge, alongside a recommended headspace of 0.040-0.041 in.
Ten minutes with a gauge confirms the firearm corner of the Triangle of Success is set up exactly as ELEY intends. With that verified, the remaining work is finding the production lot that shoots best in your barrel: book a batch test at eley.co.uk/vip, or study the proof data behind any batch free of charge at eleyxshot.com.