Rifling Machines & Methods

Rifling Machines and Methods

by Clifford F. LaBounty

I was in the reboring and rerifling business for approximately thirty years. I wrote this book with one thought constantly in the back of my mind: what information did I wish I had been able to find when I started out to become a barrel maker.

The following Table of Contents, with a brief synopsis of each chapter, will tell you what I wish I had known, and probably, what you would like to know about rifling by someone who has done it.  Perhaps you want to explore what you would need to make an occasional barrel for yourself and friends, see if you enjoy it, (you will) and maybe even sell one occasionally.  If you are starting out in barrel making, or just want to know how it’s done, then you need this book.

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1-This chapter is an overview of various rifling methods. Cut rifling, including single-point hook and scrape cutters, the saw cutter and broaches are covered. Button rifling and the draw bench methods are shown. The section on hammer forging is written by Ruger’s head of barrel making, Vern Briggs, and James Higley, Professor of Mechanical Engineering Technology at Purdue University Calumet in Hammond, Indiana. Methods of electro-chemical rifling are illustrated. Gain twist, paradox rifling, ball and shot guns, reversed paradox, Lancaster oval bore, parabolic rifling, changing groove depths and groove widths within the barrel and tapered bores and grooves are covered.
2-Early hand-operated sine bar rifling machines, plus a recently made hand operated machine, and line shaft machines, including the famous grasshopper and Pratt and Whitney overhead mounted sine bar rifler are pictured and explained. How these machines work and important design info for builders is included. A sine bar machine that produces gain twist with a straight bar is pictured and explained. The John Danskin built sine bar machines, basically a copy of the Pratt and Whitney, but converted to hydraulics, is pictured. A clever conversion of a Pratt and Whitney sine bar to produce varying depth grooves is also illustrated.
3-A series of fortunate circumstances has seen the preservation of Harry Pope’s rifling machinery and tooling. David Arawinko, the owner, has provided pictures, and in a heretofore unpublished treatise, illustrates and explains not only how Pope rifled his gain twist barrels, but has deciphered the number codes on Pope barrels. (See a description of the Addendum, after the Chapter Twelve description, for more on Harry Pope.)
4-Pictured and explained are three CNC machines built by the author, and one built by Bill McCarthy.
Follow the changes made over the years to the first hydraulic machine made by the author as it progresses to becoming fully capable of rifling a barrel with no intervention. Why it is better than the Pratt and Whitney machines for reboring is covered. Changes made by its new owner are shown.
Complete directions, illustrated by pictures and drawings for making both scrape and hook rifling heads, plus a force analysis of the hook rifling cutter. Experiments with a true hook (circular front face for positive hook) and how to make one are shown. Everything you need to know to make a professional quality rifling head.
The last cut-rifling machines built by Pratt and Whitney are independently operated, twin spindle, hydraulically driven machines. The modifications to these machines made by cut rifle barrel makers to allow changing twist rates without changing leader bars are fully covered.
Cutting tool geometry and types of machines used for gun drilling are shown, both custom built and manufactured. Included is a three-spindle, custom built drill.
9-The geometry of a modern bore reamer is illustrated. Reaming machines made from a converted lathe and the Pratt and Whitney type of machines are pictured as well as three custom made machines. Speeds and feeds are discussed.
Buttons and button rifling machines are shown, with a discussion of design features. Workable lubricants are disclosed. A real world explanation of the forces involved is shown, with data taken from a working machine.
Directions and procedures and what abrasives to use are covered. Good info on a shop-made ball bearing lapping handle is given.
The advantages of reboring and the possibilities of getting something special is fully covered. Reboring pistol barrels and side-by-side double barrel rifles are two of the unusual possibilities. Matching twist rates to deepen existing grooves, including how to match gain twist rifling is revealed.
Twenty pages of how to make a Harry Pope rifling cam and how Pope set his cam to produce his legendary barrels. Dave Arawinko, owner of the Pope rifling machine with access to many of Pope’s barrels, has cracked the number codes that are on Pope’s barrels. Pope’s cam that guided the twist rate was a parabolic curve. Dave tells you how to make your own Pope cam, if you want to use that style of rifling. Dave shows how he doped out how to position the cam on the Pope machine to reproduce as close to a Pope barrel as you can get without being Pope. Dave Arawinko has done it. On Pope’s rifling machine! Marvelous information, first time published.