Gunsmiths should be prepared to test the rifles we build and offer sound advice on some of the lesser understood aspects involved. Working with Improved or Wildcat cartridges fits right in here.

by Norman E. Johnson

An Improved cartridge is essentially an enlarged version of an existing cartridge, fire-formed or expanded in the forward half of the case body and shoulder over the parent cartridge. These cases are normally headspaced on the same neck and shoulder datum line as it is fire-formed in the new chamber. The end result is a cartridge that holds a greater volume of powder, thereby increasing its velocity and often its overall performance. The process is not always without some cartridge loss due to case cracks or splits. There are obviously caveats to be observed by the shooter if sound practices are not followed.

Typically, the reamer used for an Improved cartridge is headspaced on the neck shoulder or case datum line. As a result, the case is correctly headspaced and ready to be fire-formed, resulting in a new version of the cartridge. Attempting makeshift headspacing techniques can lead to real problems and locked up or blown rifles. One such risky procedure is to use a long-seated bullet in an attempt to establish headspace. That is where a long-seated bullet makes firm contact in the leade or throat of the chamber as a means of headspacing. There are always added problems where the Wildcat or Improved cartridges are much shorter than the chamber they are to be formed in, particularly forming rimless cartridges.

As a rule it is strongly advised to stay away from any…

Read more in the April 2020 issue.

Don’t miss a single issue. Subscribe now or renew your subscription.

For non-subscribers wanting free access, submit one free article to use on our site and we’ll send you a complete digital copy of any issue of your choice (April 2006 to current).