Sig Cross Rifle Gets a New Carbon Fiber Barrel in 6.5

in Authors, For Rifles, Gear Reviews, Steve Gaspar
Helix 6 Barrel with Sig Cross Rifle
All the good things: Helix 6 Precision carbon fiber barrel, Sig Cross rifle, SilencerCo suppressor, BT CAL Atlas bipod, Zero Compromise Optics scope, and Nosler ammunition.

Estimated reading time: 10 minutes

A while back I covered Helix 6 Precision’s carbon fiber barrels and tested one in 6ARC. As mentioned in my previous article, Helix 6 founder Jon Beagle is obsessed with quality, consistency, and accuracy. Jon is a precision rifle builder, and to put things in perspective, if you want him to build you a custom long-range rifle you can’t get one this year. A competitive precision shooter, Jon knows what he is building – in practice, not just in theory.

After only an hour in his shop, I understood I was talking to a builder of accurate things. He originally started Helix 6 Precision because he couldn’t find carbon fiber rifle barrels that were accurate enough to meet his requirements for the custom rifles he was building. His solution was to engineer them from the ground up for the specific purpose of being consistently accurate as well as lightweight. Helix 6 Precision hand lays the carbon fiber fabric rather than spindle winding. This is more expensive, but it yields a better result for making rifle barrels.

Beautiful looking Helix 6 Carbon Fiber Barrel
The Helix 6 Precision barrels are as beautiful to look at as they are accurate to shoot.

The Sig Cross

The Sig Cross rifle has had a strong following almost immediately upon its launch a few years ago. The original idea seemed to be a “cross” between the precision rifle world and the hunting rifle world. The Sig Cross is lightweight and accurate. Many of its features are normally found only on precision rifles. Another hook when it came out was the not-so-available-at-the-time .277 Fury cartridge that my editor True Pearce used on an elk hunt. The .277 Fury is still something of a unicorn, but the Cross can readily be found in .308 and 6.5. At this point, Sig offers Cross derivatives such as the PRS, the Born and Raised, and the STX. I bought one of the earlier Cross models in 6.5 Creedmoor and have been very happy with it.

Helix 6 carbon fiber barrel
Homegrown craftsmanship – Helix 6 Precision carbon fiber barrels are made in Vancouver, Washington USA.

Although a stock Sig Cross in 6.5 Creedmoor only weighs 6.8 pounds without an optic, the Cross crowd was clamoring for a carbon fiber barrel from the beginning. Supply has not met demand in this instance, partially because Sig has not made barrel extensions readily available to DIY-ers or rifle builders.

The Barrel Mechanics

The Cross barrel extension threads onto the barrel and is fixed in place by a jam nut. The barrel assembly is then attached to the receiver with a nut similar to an AR15 barrel nut. Carbon fiber barrel makers have had to deal with the fact that a barrel swap would necessarily involve taking the old barrel extension off the original barrel and reusing it. This requires headspacing and a few tools that most DIY guys don’t have. It’s hard to overstate what a barrier this is for the cross-carbon fiber barrel market.

Sig Cross Rifle Gets a New Carbon Fiber Barrel in 6.5
Helix 6 Precision barrels have hand-lapped button rifled 416R stainless steel cores. Carbon fiber fabric is then hand-laid.

Many AR15 owners are comfortable swapping and headspacing barrels. It is a straightforward process of handguard removal, barrel nut removal, barrel swap/torque, and checking headspace. It is a simple procedure involving inexpensive hand tools. Easy peasy. The barrel on the Sig Cross is easy to remove with an AR15 armorer’s wrench and a barrel vise, but that’s where the similarity in simplicity ends. This little wrinkle in Sig Cross barrel swapping has not dampened demand, and barrel makers are responding. Enter Helix 6 Precision.

Tools for installing the Helix 6 carbon fiber barrel
Tools used in this barrel swap. You need either a 1 1/16th 12-point box end wrench or the 1 1/16th flare nut crowfoot wrench to remove and reinstall the barrel extension.

I’m On It

As an owner of several carbon fiber barrels and as a Sig Cross owner I was watching this part of the market. As soon as I found out Jon Beagle was making carbon fiber Cross barrels I had to check them out. At first, the process of doing the barrel swap seemed beyond my capabilities. My hesitation had more to do with what I had read on the internet and my own AR15 builder orientation. I have zero concerns about building AR15s from the ground up. The leap to a Sig Cross barrel swap was actually easier than I initially suspected. I completed the process without a key tool I would absolutely get if I were doing even two of them – the hard-to-find Sig Cross action wrench. But the swap can be made without that tool if you have a good barrel vise and a few other things.

Sig Cross Rifle Gets a New Carbon Fiber Barrel in 6.5
Friends wanting to get together.
Sig Cross Rifle Gets a New Carbon Fiber Barrel in 6.5
Initial disassembly. Getting this far is easy. The barrel extension is the tricky part.
Sig Cross Rifle Gets a New Carbon Fiber Barrel in 6.5
This 1 1/16-inch flare nut crowfoot wrench was the ticket to remove and reinstall the barrel extension.

My Process For Removing the Original Barrel

As mentioned above, removing the Sig Cross barrel is straightforward. A Torx driver takes off the rail and the handguard. An AR15 armorer’s wrench and either a barrel vise or a Sig Cross action wrench get the barrel off. I used a barrel vise. Next, the jam nut has to be removed to free the barrel from the barrel extension. To do this you need a 1 1/16 inch 12 point wrench or flare nut crow foot wrench.

At first, I tried to remove the jam nut by putting the barrel in the vise and then wrenching the nut off. This did not work because the nut and the extension both turned. Instead, I put a three-pronged muzzle device on the barrel. This allowed me to put a breaker bar on a tool that fits into the muzzle device, thereby holding the barrel fixed. Then I put the extension itself into the barrel vise and broke the jam nut loose. It didn’t take much force to get it off.

Putting The New Barrel On

Next up I threaded the new Helix 6 Precision carbon fiber barrel onto the extension part of the way. After removing the ejector from the bolt, I put some painter’s tape on my 6.5 Creedmoor Go gauge, inserted it into the chamber, and closed the bolt. Slowly I turned the barrel onto the receiver until it was barely snug. Now I was ready to headspace.

With the barrel back in the vise, I tightened the flare nut wrench with a torque wrench set to 55 foot-pounds. Once tight I removed the Go gauge and tried my NO GO gauge. After a few tries, I got the Go to go and the NO GO to not go and my headspace was done.

READ MORE: Helix 6 Precision’s Customizable Carbon Fiber .22 Barrels — SHOT Show 2022

After that, I torqued the barrel onto the receiver using an AR15 armorer’s wrench and my torque wrench (45 foot-pounds). In this part of the process, I wished I had the Sig Cross action wrench, but absent that I just used the soft jaws of my bench vise to hold the action. Apparently, if you torque the barrel to the receiver by putting the barrel in a vise you stand the chance of moving the headspace and you have to start over.

Headspacing Double-Check

Finally, after getting the barrel on the receiver I did a double check of the headspace and was ready for the handguard, rail, and scope. There are videos of this process online. Also, the torque specs mentioned are what I did based on my research. Sig doesn’t supply any of them to the general public. I chose to do this process myself, but only you can decide if you want to do so or if you want to use a competent gunsmith. The former involves personal risk. The latter is the smarter way to go.

Sig Cross Rifle Gets a New Carbon Fiber Barrel in 6.5
I removed the ejector before checking head space.

To the Range

For accuracy testing, I used a Zero Compromise ZC527 riflescope, a direct thread SilencerCo Omega suppressor, and ammunition from Nosler and Hornady. Nosler was good enough to send me some 140g RDF and 90g Varmageddon cartridges, and I had some 140g BT rounds already. Hornady had sent me some 140g ELD-M, but I had used those up for another project. I used the Hornady 95g Varmint Express and 140g American Gunner rounds I had in my inventory already. I shot two 5-shot groups with each type of ammunition.

The best 5 shot groups of every type of ammo were sub-MOA, with the Nosler RDFs turning in an impressive 0.6475 inches at 100 yards. Some of the three-shot groups were really tight, and the worst group of all ten was only 1.2 inches. This was all done on a 100-degree day in August with 5-10 mile per hour variable full-value winds. The Zero Compromise optic was used to rule out that part of the accuracy equation, but in the field, I will put a lighter scope on it.

Accuracy using the Helix 6 carbon fiber barrel
A good day at the range. Five types of factory ammunition shooting sub-MOA five-shot groups.

Hits With The Helix 6 Barrel

Helix 6 Precision barrels are as beautiful as they are accurate. They won’t lose accuracy with long shot strings the same way that steel barrels do. Even for bolt guns this comes in handy when you are at the range practicing. You can have confidence that rapid practice is not affecting your group sizes. I ran the accuracy test in high heat as fast as I could go. The only thing that slowed me down was burning brass landing on my arm and the occasional heat mirage (I used a silencer cover to minimize the latter issue).


Really the only criticism is the cost at $1449 for a 6.5 Creedmoor barrel. But if you want super-quality American-made craftsmanship, this is your barrel.

*** Buy and Sell on GunsAmerica! All Local Sales are FREE! ***

Send this to a friend