- 01: Introduction
- 02: History
- 03: Propellants, Firearms, and Ammunition Development
- 04: Modern Firearms Manufacture
- 05: Small Arms Ammunition
- 06: Evidence Handling Procedures
- 07: Equipment and Instrumentation
- 08: Examination of Firearms
- 09: Cartridge and Shotshell Examination
- 10: Characterization and Evaluation of Fired Projectiles
- 11: Bullet Comparison and Identification
- 12: Gunshot Residue and Distance Determination
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
Smokeless Primers
Home > Propellants, Firearms, and Ammunition Development > Evolution of Ammunition > Primer Evolution > Smokeless Primers
In the 1920s, lead styphnate was used as an initiating compound because it did not produce corrosive residues. Many other mixtures were tried and some were released for market trials. The combination of materials that worked best was a blend of lead styphnate, antimony sulfide (fuel), and barium nitrate (oxidizer). By the 1930s, all U.S.-made commercial primers were using this basic formula.
Styphnate priming compounds may contain other materials in addition to the three main compounds, such as the following:
- Sensitizer - makes the material more shock sensitive. The most prevalent sensitizer is tetracene.
- Finely powdered aluminum - added fuel used to project incandescent particles into the propellant.
- Organic binder - keeps the dried primer pellet consolidated, e.g., gum acacia.
- Dye - facilitates visual inspection of primers during manufacturing.
A Boxer primer used for a rifle or handgun has a minimum of three components: the metal cup, the priming compound, and the anvil. Many have an additional component—a thin paper cover between the compound and the anvil. This is known in the industry as the foil paper because original percussion caps had a layer of foil over the mixture for protection.
Shotshell primers are more complex. Because the shotshell case is largely nonmetallic, an extra part, the battery cup, is added to better support the anvil and resist operating pressures. In addition, the large flash hole has a paper or thin plastic cover, a relatively recent feature.
The lead styphnate percussion primer has remained nearly unchanged in form or chemistry since the 1930s. The discharge residue of these primers contains lead oxides and nitrates. Recent concerns over airborne lead in poorly ventilated indoor ranges have led to the investigation of lead-free primers and toxic metal-free primers. Future primer development will undoubtedly focus on additional improvements to low-toxicity compounds.
