Carbon Wrapped Barrels
Bettin Custom Guns builds our own light weight carbon composite reinforced barrels in-house. With the help of SES Prototyping we developed what we think is a better composite wrapped barrel system. Using our proprietary manufacturing method and improved composite materials, we developed a lighter, more accurate hunting rifle barrel. We put our composite materials on high quality Satern cut rifled barrel blanks that are specifically manufactured for our process by Satern Custom Machine in Estherville, IA. We put a .5 moa accuracy guarantee on all the rifles we build with our barrels. When we shoot these rifles for accuracy testing, we do not wait between shots for the barrel to cool in order to meet our accuracy standards. In our hands, in our 100 yd indoor shooting tunnel, we are not satisfied unless we can consistently shoot SUB .5 moa, 3-5 shot groups.
Common Questions, Concerns, & Skepticisms of Carbon Wrapped Barrels
1 ) The barrel will warp as it heats up, creating stringing or opening up of the groups after successive shots.
Our answer to this problem is very simple. The reason point of impact changes with any level of heat is entirely due to the internal stresses in the steel of the barrel. The ONLY manufacturing process that absolutely assures there is no internal stress on the barrel is single point cut rifling. Even a very thin barrel that is cut rifled will not change point of impact as it heats up. The only negative with such a barrel, is that it is not as stiff as a bigger barrel and thus accuracy can be affected because the barrel is more flexible then a heavier barrel. Our carbon process simply replaces the stiffness with a much lighter substance. We basically get the accuracy of a heavy contour barrel, with the weight of a super light. Satern Custom Machine contours our barrel blanks specifically for our process with all the contouring and machining done to them BEFORE they are rifled. This is done to ensure that NO stress is induced in the barrels we use, so heat does not affect them to any significant degree. The barrel liners are designed with enough wall thickness to withstand the pressures with a 200% safety factor. The composite sheath only enhances the barrel’s stiffness; we DO NOT rely on the composite for burst strength.
So why don’t all the carbon barrel manufacturers use single point cut rifled barrels?
Simple, they are expensive and time consuming to make. Higher prices and long turnaround time is a negative factor in mass production. We don’t, nor do we want, to compete in the mass production market. Our mission is to build a relatively small number of very high quality rifle barrels for a select group of rifle connoisseurs.
2 ) The carbon insulates the barrel heat and increases the rate of throat erosion.
The engineers at SES prototyping did testing and extensive calculations about what happens in a barrel when a round is fired. They took into account the pressures, heat, metallurgy and as many other variables as possible.
Their findings are probably not a new discovery in the gun world; it’s more the fact that they put the actual numbers and science to some of the theories and misconceptions that exist. Their calculations showed that the very inner lining of steel in a barrel was stressed beyond its heat and tensile strength limits for a few milliseconds with every single shot. This repeating stress cycle changes the lining of the steel at the molecular level, causing micro cracks in the surface of the steel. The rest of the steel in the barrel keeps it from bursting and help it spring back to its original size. The temperature of the steel in the outer layers of the barrel had very little effect on these changes.
They also found that the abrasive nature of gun powder is also responsible for a large portion of the erosion taking place. Basically, with every shot we are running abrasives (un-burned powder) down the barrel.
“Throat erosion is the result of the micro-cracking of the material under pressure in combination of the heat and sandblasting effect of the gun powder leaving the case”
The Big over-bore cartridges have more unburned powder, thus more abrasives, thus they erode faster. Smaller cartridges, and cartridges with very efficient burning of the powder column (short mags, PPC etc), have less unburned powder and the result is longer barrel life. The quality of the steel, as well as coatings (nitride coating, chrome lining etc) extend barrel life by being more resistant to these factors. In reality the temperature of the outside of the barrel effects throat erosion very little in all but the most extreme situations.
Thus throat erosion continues despite any attempts to keep the barrel cool. In situations of extreme barrel temperatures, removing heat from the outside surface will definitely extend the number or rounds barrel can fire until the outer layers of the barrel reach critical temperature and the steel in the barrel literally starts to get soft. At those extreme temperatures of course barrel life is reduced dramatically, but that would be in a full auto or extended rapid fire semi auto situation. Hence the reason for water cooled automatic weapons and quick change barrels.
That is not what our barrels are designed for.