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The 'Delta L problem' occurs when a CIP minimum sized chamber in a firearm is shorter than a non CIP maximum sized cartridge. This leads to chambering and/or feeding problems in the shoulder area.

Contents

Conflicting industry standards

Delta L cartridges list

References

Conflicting industry standards

The main cause for the Delta L problem is that the two main ammunition and firearms industry standards organizations CIP^[1] and SAAMI have assigned different standards for the some cartridges. This leads to officially sanctioned conflicting differences between European and American ammunition dimensions and chamber dimensions and maximum allowed chamber pressures.
Generally hunting rifles in CIP regulated countries are not cut to the minimum CIP chamber dimensions so this problem is mostly theoretical. The hunting rifle manufacturer SIGARMS sister companies Blaser and Mauser are however know for hammer forging tight (but still CIP conform) chambers in their Blaser R93 and Mauser M03 switch barrel rifles and some hunters reported Delta L problems with ammunition imported from non CIP member states in those rifles. These problems can also occur with other European made rifle brands.

Delta L cartridges list

The German gun tools manufacturer Triebel published a Delta L cartridge and theoretical CIP minimum chamber length shortage dimensions list. Most cartridges on the list are of American origin. The first European cartridge that can exhibit Delta L problems is the 6 x 47 SM (Swiss Match). This is a 300 m match cartridge primarily used by the Swiss 300 m team (The Swiss team is often world champion in this discipline). The second European cartridge that can exhibit Delta L problems is the 9.3 x 66 SAKO. This is a fairly new Finnish hunting cartridge. The table shows the .30-06 Springfield cartridge family with about 0.15 mm (0.0059 in) theoretical chamber length shortage to be the most prominent Delta L problems candidate.

References

★ Triebel Guntools
1. The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (commonly abbreviated as C.I.P. or CIP) is a European ammunition standards organisation. CIP publishes various industry standards such as ammunition and chamber dimension specifications and maximum allowed chamber pressures that have undisputable legal status in CIP member states. Its American equivalent is the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI).