Historical precedents for gain twist barrels and more urban legends.
by Joe Carlos
Let’s fast forward from Pope’s barrel making era about a century ago to the “modern” rifling methods. Most hunting rifle barrels and a fair number of military and custom barrels are rifled using the button method. As you know, the button method does not cut the grooves out but simply displaces metal in a swaging process. Button rifling is much faster to accomplish and that helps reduce costs as compared to cut rifling methods. One of the criticisms of the button method, however, alleges that the twist rates of some barrels can vary just a little, adversely impacting on accuracy. While the average hunter trying to bag a deer or a Soldier shooting similar sized two legged targets, both at similar modest distances, might not notice any accuracy degradation, some high end snipers and all competition shooters involved in Bench Rest, High Power and all the long range disciplines have greater accuracy standards.
As the legend was told to me, someone made up a “twist rate checker” of some sort. Button rifled barrels were subjected to testing and some were found to vary a little in twist rate A high correlation was found between accuracy and how the twist rate varied. Remember, these are uniform twist barrels that are supposed to have a uniform twist rate from back to front and not gain twists. Allegedly, barrels whose twist rate became a little faster toward the muzzle were more accurate than ones whose twist rate became slower from back to front (really undesirable) or barrels whose twist rate didn’t vary at all.
The Future Of Gain Twist
I mentioned at the beginning of the article that gain twist has been on again and off again for over a century and a quarter that I am aware of, perhaps even longer. Today we have some really premium barrel makers turning out gain twists and I believe we better understand the improvements they can offer.
Read more in our December 2013 issue. Back issues are available.