Masters Theses

Keywords and Phrases

Flash hole


"The objective of this research is to determine the effect of dimensional and positional changes of the primer flash hole on the performance of factory-grade rifle ammunition. The studied variables were flash hole diameter, offset from center, and orientation of the offset in the primer pocket. Cartridge performance was quantified by measuring muzzle velocity, chamber pressure, and target grouping size (precision).

Five different flash hole diameters were tested for both the Remington .223 and Winchester .308 calibers: 1.4mm, 2.0mm (the Fiocchi standard), 2.4mm, 2.8mm, and 3.0mm. Each diameter was tested at three offsets: centered (no offset), 0.5mm from center, and 1.0mm from center. Each of the 0.5mm and 1.0mm offsets were tested at three orientations: up (12 O'clock), side (3 O'clock), and down (6 O'clock). Every flash hole was manually drilled and each cartridge hand-loaded in order to conduct controlled testing of the flash hole variations. Testing took place in two segments with the muzzle velocity and precision measured at a private range outside Rolla, MO and chamber pressure and a second muzzle velocity measured at Fiocchi of America (Ozark, MO).

Results showed that muzzle velocity and chamber pressure varied 1-4% from the control flash hole as hole diameter, offset, and orientation changed. The precision, particularly in the 3mm diameter and centered flash hole cases resulted in improvements of up to 28%. Variations in flash hole diameter, offset, and orientation do affect cartridge performance. Alternate flash hole diameters exist that improve powder ignition consistently as well as precision. Off centered flash holes increase target grouping size and result in less consistent muzzle velocity and chamber pressure values."--Abstract, page iii.


Worsey, Paul Nicholas

Committee Member(s)

Worsey, Gillian M.
Baird, Jason, 1955-


Mining Engineering

Degree Name

M.S. in Explosives Engineering


Missouri University of Science and Technology

Publication Date

Spring 2015


xiii, 255 pages

Note about bibliography

Includes bibliographical references (pages 253-254).


© 2015 Nicolaas Martin Schrier, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Ballistics, Interior
Propellants -- Testing

Thesis Number

T 10694

Electronic OCLC #