There's a fast and easy way to check the headspace in a Winchester Model 94 in 30-30 and other cases based on a 30-30 case. The Sporting Arms and Ammunition Manufacturer's Institute (SAAMI) specifications call for a Minimum of .063" and a Maximum of .070" headspace in 30-30. |
SAAMI defines headspace as : "The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats."
Since the 30-30 headspaces on the rim, its headspace is the distance from the front of the rim of a seated case to the face of the bolt. To determine that distance we:
In our example, .058" + .011" = .069" or borderline maximum headspace. The example rifle might misfire occasionally with factory ammo, but it will probably shoot reloads just fine.
- Measure the rim thickness of a new case. A fired case will have expanded and closed the headspace. You must use a new, i.e., unfired case. Measure around the rim and use the highest value obtained. For an example, we'll say it measures .058".
- Take a fired primer and start it into the unfired case's primer pocket. Seat it just enough that it doesn't fall out.
- Hand chamber the new case, and slam home the bolt, seating the fired primer with the bolt.
- Remove the case from the rifle's chamber, and measure the distance the primer protrudes from the case head. For an example, we'll say it protrudes .011".
- Add the rim thickness measurement to the primer protrusion measurement and you have your rifle's headspace, at least you have a close approximation of its headspace.
Note: this quick check method is not meant to replace headspace gauges!
Copyright 2004 by Junior Doughty