2. Genuine Forsyth Rifling


R.J. Renner employs Genuine Forsyth RiflingTM - a very unique method of rifling gun barrels - which serves several purposes and results in attributes unique to our rifles. Before one can appreciate the Benefits of this rifling, however, it is helpful to understand a simple, yet monumental, Fact which has heretofore been overlooked or simply not understood. And that is...

Due to the fact that the sphere is a Perfect geometric form, it has been observed that very little rotational spin is necessary to accurately stabilize the large (calibre 58 and larger) round ball in flight.

This simple fact has brought us to scrutinize, under the Light of Engineering Principles, the conventional rifling of barrels. The conclusion of which having resulted in our utilization of very slow-pitch rifling. This action seems to incite anger and hysteria in some otherwise open-minded people. But, be it known that this Process is founded in the Sound Principles of Science and not born of an afflicted mind. 

~Consider the Rail Train~ 

The advantage of the principle of slow rifling can be easily understood, even by those of little formal schooling, through the following analogy:

Consider for a moment the rail train about to negotiate a curve in the track. If the curve be slight, the train may be able to take the curve at its full speed. But, if the radius of the curve is decreased, that is to say, if the turn be a tight one, the train must decrease its speed or it will surely fly from the rails as it rounds the curve.

-->In the same way, a ball traversing a barrel of the conventional rapid rifling twist, a sharp curve, if you will, is limited in its Potential to achieve high velocity lest it strip from the rifling as the train would be stripped from the track. In the case of the former, the loss is accuracy. We shall not want to contemplate the fate of the latter.

Remember this simple axiom: The sharper the curve (the faster the pitch of rifling) the slower the train (the ball) must be driven if it is to arrive at its intended destination.

The magic Forsyth formula is simply 1/4 turn of rifling in 
the length of the barrel for the highest velocities.

In addition to providing the Accuracy that we demand of our rifles, it has been further observed that our slow rifling, bearing but a pitch of 1 turn in 100 inches, provides the Highest velocities to the patched ball with very little stress imparted to the Faeton rifle.

In one such test, our 20-bore barrel was loaded with 200 grains of FFg black rifle powder and patched round ball and produced velocities exceeding 1,800 feet per second.

Such high muzzle velocities - above 1,500 feet per second - produce a Flatness of trajectory with superior knockdown power to 150 yards that is the envy of riflemen shooting the recently popularized lightweight sabot/bullets in their various forms.

Despite the improvements made to these newer projectiles, our contention remains that the Round Ball of Large Calibre, driven to high velocity, is far and away a Superior projectile for dispatching large game in a humane and Sportsman-like manner, within reasonable sporting distances, that is to say, 125 yards.

In addition, our Genuine Forsyth RiflingTM features wide, shallow grooves and very narrow lands which afford little area for the accumulation of powder fouling and further allows for use of hardened lead balls  for greater penetration on large, tough game with full retention of accuracy.

Fast Forsyth RiflingTM
Recently we have added our own Fast Forsyth Rifling which features the wide, shallow grooves and its attendant advantages with a quicker twist which provides better accuracy to loads at the lower end of the power spectrum. 

Forsyth Shotgun?

Also, when properly loaded, the Forsyth bore will shoot shot loads with cylinder-bore patterns to 20-25 yards, the slow twist of the rifling having little adverse effect upon the pattern.  By utilizing a shotcup and droge, as seen below, the resulting pattern remains remarkably dense at much greater distances.  

When shot from a rifle-sighted Faeton, tight-shot patterns can be accurately delivered at long range on smaller game, such as turkeys.

If you would like to receive a pdf copy of the Second Edition of Forsyth's wonderful book, THE SPORTING RIFLE AND ITS PROJECTILES, please send your request to us by email at: rjrenner@protonmail.com

Additional information regarding Forsyth rifling may be found on the site of The Underhammer Society at:

Copyright by RJ Renner

About Me

Hi. I've been a student, admirer, designer, and builder of underhammer firearms for over 30 years. In that span I've crafted over 200 high-quality Forsyth-rifled underhammer guns, having explored the possibilities from the ordinary to the exotic. In 1996 I founded Pacific Rifle Company to explore the market's interest in a quality underhammer rifle. The justly-famous Zephyr was the result of that effort. Thankfully, there was and still is great interest in quality underhammer arms. Although I sold PRC in 2006, I continue to design and craft high-end underhammers as I am truly afflicted with underhammeritis - a condition which can be contagious!