They’re not fully carbon fibre. The inner core of the barrel is steel, but it’s relatively thin. The layers of carbon fibre are then wrapped around it to get the compressive strength you’d need a lot of steel to achieve. So you get the same or better accuracy at a lower weight.
The tradeoff is the barrel loses a ton of thermal mass which means they heat up very quickly. Not so good for a combat rifle.
They’re not fully carbon fibre. The inner core of the barrel is steel, but it’s relatively thin. The layers of carbon fibre are then wrapped around it to get the compressive strength you’d need a lot of steel to achieve. So you get the same or better accuracy at a lower weight.
The tradeoff is the barrel loses a ton of thermal mass which means they heat up very quickly. Not so good for a combat rifle.