SIG Sauer Cross Magnum in .300 Win. Mag.: Full Review

Sig Sauer’s Cross Magnum may indicate just how much the shooting and hunting community is changing. The first Cross rifle was introduced in 2020 with low weight and high accuracy as two of its design criteria. It was developed to be a rifle that could be good for anything. Lightweight hunting rifles with folding adjustable stocks and long multi-­purpose forends capable of accepting night vision devices are trending. The Cross Magnum adheres to these principles, but was made for the .300 Winchester Magnum chambering.

The Cross Magnum uses a unique one-­piece aluminum receiver, the heart of the rifle. Instead of bolting a receiver to a stock or chassis, SIG Sauer created a receiver that also functions as a chassis. The buttstock assembly and forend attach directly to the receiver, so there is no need for a traditional stock and action screws. Action screws can work loose at the most inopportune times, so their removal eliminates a common source of rifle accuracy troubles. Likewise, the magazine feeds directly into the receiver without relying on bottom metal and internal pillars to correctly organize the relationship between the magazine and rifle. Thanks to this slimming down, the Cross is a rifle with fewer fasteners and fewer components that can fail.

The unique receiver houses a three-­lug bolt that locks into a steel barrel extension, which is threaded onto the barrel. Cross bolt lugs are unlike any other. They are long, giving them prodigious contact with the rest of the bolt head. They are heavily radiused to make it extremely difficult for cracks to form. The back of the bolt lugs that sit against the lug abutments in the barrel extension are angled to further reduce the likelihood of cracks forming, and to increase the bearing surface against the lug abutments. The result is strength.

Once the bolt slides home, the steel components contain all the pressure. This thoughtful arrangement allows SIG Sauer to make the rest of the rifle out of aluminum to minimize weight. While some might be tempted to look at the aluminum receiver body and think the Cross Magnum is fragile, nothing could be further from the truth. The Cross was originally designed around the .277 SIG Fury and its 80,000 pounds per square inch (psi) maximum chamber pressure. Prior to the .277 SIG Fury, 65,000 psi was the maximum allowable chamber pressure. This doesn’t mean that Cross Magnum owners should begin loading rounds that exceed the .300 Winchester Magnum’s 64,000 psi maximum safe chamber pressure, it’s just that the rifle is one of the strongest bolt-­action designs on the market.

SIG Sauer did two desirable things to the Cross Magnum to make it unique among factory offerings chambered in .300 Winchester Magnum. The first was to build it around a magazine capable of housing cartridges with a 3.85-­inch length. This leaves about .25 inch of space in front of the bullet’s nose when the cartridges are loaded in the magazine. Devotees of the .300 Win. Mag. have an unprecedented amount of space to seat long bullets in the case. Moving the bullet up and out of the case gets it out of the powder column, a problem for the longer, heavy-­for-­caliber projectiles because those projectiles can be bent or pushed off the axis when the powder ignites.

Moving the bullet out of the powder column also frees up space for more powder, giving the Cross Magnum access to performance not possible from other rifles. The additional case volume allows what would have been a maximum powder charge to burn at a lower chamber pressure because the same powder charge in a larger container creates less pressure. While it might be tempting to think that lower chamber pressure equates to lower velocity, this is not true. Gas volume is what creates velocity. The additional case volume that results from seating bullets long in the case gives those who handload for the Cross Magnum access to untapped potential and untapped velocity. Of course, Guns & Ammo encourages everyone to stay below the maximum powder charges in published reloading manuals.

The second subtle change SIG Sauer made was to tighten the barrel twist rate from the traditional 1-in-10 inches found in other .300 Win. Mags to 1-in-9-inches in the Cross Magnum. This change, when combined with the magazine selection, allows for the 190- to 230-­grain projectiles to shine when used in the Cross Magnum. Faster twist rates are necessary to stabilize heavier bullets, especially at the relatively mild .300 Winchester Magnum velocities. One temptation about twist rates is to always think that faster is better, so it’s not uncommon to hear the call for 1-in-8-inch twist for .30-­caliber magnums. The 1-in-9-inch twist is plenty for anything up to 230 grains, though. Faster twist rates than necessary usually bring some trouble with them. Bullet revolutions per minute can increase to the point that jacket integrity becomes compromised, especially when the barrel is hot, which happens fast with a long-­action magnum. Faster twist rates also generate more torque on the rifle, making it harder to achieve maximum precision. Magnum rifles have to be held more firmly when fired because of the torque they generate, so keeping torque to a minimum is always a good idea.

The Cross Magnum weighs 9 pounds. A lot of the weight comes from the medium-­contour, 24-­inch stainless-steel barrel. It would be possible to lose between 8 and 16 ounces by installing a carbon-fiber barrel, should weight be a significant priority. The handguard is 18 inches long and has M-­Lok slots cut into its length around the circumference. The bottom of the handguard has an integrated ARCA rail that allows for quick attachment and repositioning of a bipod or tripod. The long handguard also gives the shooter plenty of options for supporting the forend off any field rests that might be available.

The buttstock assembly folds on the Cross Magnum, making it possible to shrink the long-­barreled magnum to a petite 36 inches in length for transport. Anyone putting this rifle in the trunk of a car or flying with it will appreciate the ability to use a compact rifle case. The buttstock retains all of the adjustability for which Cross rifles are known. Move a throw lever and the spring-­loaded cheekpiece lifts to the shooter’s cheek. A thumbscrew loosens the adjustment bar to quickly set length of pull. That same bar has some additional holes drilled in it to prevent movement when the rifle recoils. One buttstock adjustment feature that is particularly endearing is the push-­button release for buttpad height. This allows the shooter to raise the buttpad 11/2 inches higher. Moving the buttpad into this position is vital when shooting in the prone because it increases the amount of contact between the buttpad and the shooter’s shoulder. Spending a day shooting a magnum rifle requires attention to small details such as this to make the experience as enjoyable as possible. SIG Sauer got all of these details right.

The Cross Magnum is a rifle with some unique attributes that offers untapped performance from the .300 Winchester Magnum. It is a highly adjustable and well-­mannered rifle that makes it possible to spend days at a time hunting or ringing steel.

SIG Sauer Cross Magnum 

• Type: Bolt action
• Cartridge: .300 Win. Mag.
• Capacity: 6 rds.
• Barrel: 24 in.; 1:9-­in. twist
• Overall Length: 45.1 in. (extended); 36 in. (folded)
• Weight: 8 lbs., 14 oz.
• Stock: Aluminum, folding, adj.
• Grip: SIG Sauer
• Length of Pull: 11.75 in. (collapsed); 14 in. (extended)
• Finish: Anodized, coyote (alum.)
• Sights: None
• Safety: Two-­position selector
• MSRP: $2,499
• Manufacturer: SIG Sauer, 603-­610-­3000, sigsauer.com

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