Every barrel has a story to tell. Some will tell you right off that they don’t like the taste of certain types of ammo, be it the manufacturer, bullet style, weight and/or velocity. If a barrel doesn’t like the ammo, accuracy will not be good. Heat is another issue that can erode accuracy, and in my experience, as barrel temps rise, group size expands, printing higher than the initial group.
This all had me thinking, especially after playing around with a Springfield Armory Waypoint with a BSF Systems carbon-fiber barrel and a Savage UltraLite with a Proof Research barrel. I thought it would be interesting to see how hot barrels heated up and how accuracy was affected. I added steel barrels—a medium-heavy contour and a fluted one—to the mix to see if there were any differences.
I think a lot of shooters feel there is some black magic going on with carbon-fiber barrels, and fluted-steel barrels, too. Are these cosmetic features, or are they functional? Is it all sizzle and no steak? Well, by the time I was done shooting there was plenty of sizzle to the barrels—they did heat up fast.
My starting point was caliber. I chose 6.5 PRC, which is quickly gaining popularity for everything from competitive shooting to hunting to long-range marksmanship. As mentioned, I shot it through a carbon-fiber barrel manufactured by Proof Research and another by BSF Systems. The steel barrels were Savage factory units: a fluted-steel one and a medium-heavy-contour steel model. To keep the playing field as even as possible, I used the same type of action for all four barrels: a Savage Model 110, and all rifles featured Savage’s AccuTrigger. Savage offers the Proof Research barrel on Model 110 variants, and I used a 110 UltraLite. The medium-heavy-contour barrel was on the 110 Trail Hunter, and the fluted-steel barrel was on a 110 Tactical model. I had the BSF Systems’ barrel installed in a Savage Model 110 UltraLite action. Each of the barrels were 24 inches in length.
For 6.5 PRC ammo, Hornady Precision Hunter loaded with a 143-grain ELD-X bullet was used. We all know that some guns like certain ammunition brands, bullet weights and types more than others. I was just looking for consistency in groups, no matter how tight or open the groups would be. All of these barrels delivered darn good accuracy with the Precision Hunter load, right up until they didn’t.
The testing process was simple: Measure the temperature of each barrel after a five-shot group, and after a 15-shot group. Between the five- and 15-shot groups, I allowed the barrels to cool down close to the starting temperature. A laser thermometer was used to collect barrel temperature at the chamber and muzzle. Inter- estingly, the temperature at the chamber was less than the temperature at the muzzle after shooting.
Groups were shot at 100 yards using the same bipod and toe bag with each rifle, and I fired the rounds off quickly. The goal was not to say one barrel is better than another, but to observe the effect of heat on accuracy. I’ll also add that all of these barrels were broken in prior, and all had nearly the same round count through them.
Shooting took place in temperatures that ranged from the mid- to high-80s, and there was wind—there’s always wind on the coast of North Carolina—that ranged from 3 to 5 mph. That’s not enough wind to drastically change the point-of-impact at 100 yards, but enough to help cool down the barrels a bit.
Having reasonably leveled the playing field, we began our investigation. Here’s what the barrels had to say:
Medium-Heavy-Contour Steel Barrel: Bring It On
The medium-heavy-contour steel barrel in the Savage 110 Trail Hunter is made of carbon steel and is heavier than a skinnier, sporter-style barrel. Not only is the barrel heavier, it is also more rigid and stiffer due to the extra steel. Medium-heavy-contour steel barrels are better able to handle the heat that longer shot strings create. They also have more surface area, so, in theory, the barrel cools down quicker. Starting barrel temperature was 84 degrees Fahrenheit.
Holes from the first three shots kissed each other with a .34-inch group, but by the fourth and fifth shots started to open up to 1.5 inches, with a slight-but-noticeable shift upward. After the five-shot string, barrel temperature at the chamber was 91.2 degrees and somewhat warmer 99.3 degrees at the muzzle. Starting the 15-shot string with a cool barrel, the 6.5 PRC rounds heated the chamber to 104.2 degrees and the muzzle to 126.3, while groups grew to 2.65 inches. The barrel also cooled slowly.
Results
The medium-heavy-steel barrel had some change in point-of-impact as the barrel heated up and was slow to cool down. Its added heft can help manage recoil when shooting powerful cartridges.
Fluted-Steel Barrel: Off Its Meds
Flutes on the 110 Tactical barrel shave a modicum of weight. There was no real difference in felt recoil between the medium-heavy steel barrel and the fluted barrel. A fluted barrel, however, is a two-edged sword. While the flutes increase surface area, enabling the barrel to cool quickly, they also heat up faster. The first three shots out of the fluted barrel produced a 1.15-inch group, and from there it only got worse. After the five-shot string, the group mea- sured 3.85 inches. It looked like the fluted barrel didn’t like the Hornady 143-grain bullets. Barrel temp at the chamber was 98.8 degrees and 102.5 at the muzzle. Moving to the 15-shot group, the fluted barrel acted schizophrenic, or at least it had a bad case of indigestion. Accuracy eroded to a 5.2-inch group, with hits striking higher. Temperature at the chamber was 107.4 degrees and 115.1 at the muzzle.
Results
The fluted barrel cooled slightly quicker than the medium-heavy steel barrel, but slower than the carbon-fiber barrels. The heat and bullet type did not mix well with this particular barrel.
Proof Research Barrel: Who Are you Calling A Lightweight?
The advantage of carbon-fiber barrels, like the Proof Research barrel in the 110 UltraLite, is weight savings without the loss of rigidity. Proof Research claims up to 65-percent weight savings. Basically, all carbon-fiber barrels are built using a steel liner; this is the actual barrel that is rifled. The liner is then covered in carbon fiber. Proof Research wraps the steel liner with carbon fiber and uses epoxy to bond the carbon fiber to the liner. The question is: Will the epoxy, steel liner and carbon fiber all heat up at the same rate and play nice with each other, or will they heat and cool at different rates and work against each other?
The first three shots out of the Proof Research produced a nice .45-inch group. By the fifth shot, the group size increased to a tolerable 1.05 inches. Temperature at the chamber was 92.3 degrees and 108.5 at the muzzle. The 15-shot group expanded to 3.85 inches as the chamber heated to 108.3 degrees and the muzzle to 117.5. The Proof Research barrel cooled notably faster than either the medium-heavy-steel or fluted-steel barrels.
Results
The benefits of the Proof Research barrel are good accuracy and light weight. The heat was not its friend, but it wasn’t for any of these rifles. Felt recoil was more pronounced with this lighter barrel from Proof Research.
BSF Systems’ Barrel: It’s Tubular
The BSF Systems’ barrel in the 110 UltraLite also has the advantage of light weight and rigidity. BSF builds its barrels using a carbon-fiber sleeve that is under tension around a fluted-steel liner. According to BSF, 95 percent of the carbon fiber does not touch the liner, creating an air gap around the liner that allowed it to cool faster. What was surprising about the BSF barrel was how little it reacted to heat compared with the other barrels. The five-shot group measured .70 inch and the barrel temperature at the chamber was a mere 86.6 degrees, with a reading of 91.7 degrees at the muzzle. After the 15-shot string, the BSF barrel seemed nearly unfazed by the increase in temperature. The group measured 2.65 inches, while chamber and muzzle temps ran 98.7 and 112.2 degrees, respectively. Recoil was more noticeable due to the lightweight barrel.
Results
The BSF Systems’ barrel barely heated up after the first five-shot string. It cooled down fast compared with the other carbon-fiber barrel and the steel barrels. This barrel produced the tightest 15-shot group, with barrel heat having the least effect on accuracy.
This is just a simple illustration of how a particular load reacted in four different types of barrels, but the results are nevertheless interesting. So, what’s the take away? Heat does erode accuracy, and depending on the type of barrel and how many shots are fired, accuracy erosion can come more quickly.
