Running the Big Dog: SIG Sauer SIG50 Rifle

Dave Starin, former Yavapai County Sheriff, Arizona SWAT team member and currently the Training Director at Gunsite, with the SIG50.

When it comes to downrange power and accuracy at long distance, the .50 BMG round is king.

Besides its use in the venerable Browning M2 machine gun, the round is probably best known in the role of a long-distance sniping round, but the .50 BMG is also capable of taking out vehicles and penetrating cover that would be impossible for almost any other cartridge—especially at extended distances.

SIG GOES BIG

One of the latest contenders for this high-powered round is the SIG Sauer SIG50, a magazine-fed bolt-action rifle. Although it can be fired offhand, the rifle tips the scales at 23.5 pounds unloaded and without optics, and is best fired from a bipod or other support.

The length of the barrel with the muzzle brake is 29 inches, with a 1:15 right-hand twist. The heavy profile barrel is fluted from approximately eight inches from the end of the chamber to six inches from the end of the muzzle brake, which appears to be the proven McMillan design as used on the McMillan Tac-50.

To fit in a smaller case for transport, the SIG50 utilizes a removable stock. Overall length with stock attached is 57 inches. With stock removed, it measures a “compact” 46.1 inches long.

An adjustable cheek piece is attached to the comb of the stock, and length of pull (LOP) can be adjusted via four spacers in front of the rubber butt pad. The butt pad itself is the superb Pachmayr Decelerator™.

There are four socket-type sling swivel mounts on the stock, one on both sides at the rear of the stock and one on each side at the front of the forend. The massive bolt is fluted to reduce weight, and the bolt handle is smooth for easy operation with or without gloves.

The SIG50 uses a two-position safety. An adjustable trigger is set at the factory to break cleanly at 3.5 pounds. A true M1913 Picatinny 30 MOA rail is mounted on the top of the receiver. Magazine capacity is five rounds.

Included with the SIG50 is a heavy-duty steel bipod that adjusts from approximately 11 inches collapsed to 16 inches when fully opened. The bipod swivels but does not pan. Finish is anti-glare Duracoat in Flat Dark Earth.

Left side of SIG50.


READY FOR THE RANGE

For optics, I mounted a Millett BK51001 TRS (Tactical Rifle Scope) on the SIG50 using quick-detach Warne rings.

The TRS is a 4-16X scope with 50mm objective lens and 30mm tube. The reticle is a Mil-Dot Bar with adjustable green illumination—ten brightness settings plus one for night vision. The click-adjustable windage and elevation knobs are 1/8-inch clicks, allowing very precise adjustment. The side focus knob is marked with numerous yardage graduations from ten yards to infinity.

Double Tap, Hornady and Summit generously provided ammunition for the evaluation. The Double Tap load was their Match offering that uses the 750-grain Barnes TAC-LRBT bullet. Hornady sent their Match 750-grain A-MAX round. The two offerings from Summit included their 649-grain M33 Mod 1 ball loading and 750-grain Match round using Hornady A-MAX bullet.

Massive bolt is fluted to reduce weight.


With the stock removed, the rifle was transported to the range in the hard-sided fitted Pelican case that comes with it. The stock attaches securely to the receiver via a massive screw-on collar with an inside diameter of 1.5 inches. A stud inside the collar matches up to a hole in the receiver, and when the collar is screwed on tight (left-hand thread), there is absolutely no wobble or play.

On most stocks equipped with spacers to change the LOP, the butt pad must be completely removed, spacers removed or added, and the butt pad replaced. To remove spacers on the SIG50, the butt pad screws are slightly loosened with a 3/16-inch Allen wrench, the desired spacer is pushed up and away from the lower stock screw and rotated to the left away from the upper stock screw and removed. The screws are retightened and the LOP change has been accomplished. Simple and effective.

Rifle comes with sturdy steel bipod.


DESTINATION GUNSITE

I met with Dave Starin, former Yavapai County Sheriff, Arizona SWAT team member, and currently Training Director at Gunsite, for some long-range shooting.

I was going to get a rough zero with ball ammo but for some reason the Summit ammo would not chamber. I could close the bolt on a round, but could not turn the bolt handle down to engage the locking lugs.

Switching to Hornady Match, we zeroed the rifle at 200 yards and had a group just under an inch, or ½ MOA. I was excited about getting on with the rest of the evaluation and shooting the SIG50 at truly long distance.

Right side of stock shows quick-removable spacers.


A special long-range rifle course was being conducted at Gunsite, and I asked Instructor Mike Moore to invite the small group of four students to partake in the shooting. Upon arriving at the proper range, I gave a short briefing to the class about the rifle, scope and ammunition.

The first shooter got behind the rifle and loaded up with Summit Match ammo. Moore asked him to shoot at the first target, about 900 yards out. With the correct adjustments to the scope made, he scored a first-round hit. Shooting at a target at 1,100 yards, he just missed it. Moore advised him of wind, elevation and windage corrections, and the third round made a solid hit.

And then the evaluation took a turn for the worse.

Muzzle brake proved effective.


EVALUATION GOES SOUTH

The bolt would not retract, with the case firmly stuck in the chamber. Several people, myself included, tried to get the bolt to retract, and eventually it had to be tapped to the rear with a padded mallet. I looked at the case and there were no signs of overpressure.

As I was getting ready to load the magazine for the next shooter, one student asked, “Is that a crack in the stock?” Sure enough, there was a visible crack in the stock in the forward area of the magazine well.

At this point I called a halt to further shooting. The .50 BMG is a very high-pressure load and I was not going to take the chance of anyone getting hurt, since I did not know the extent of the damage to the stock other than what was visible.

Rifle was tested with Millett BK51001 TRS, using quick-detach Warne rings.


If I were to take a wild guess, it would be that the sample rifle had a rough place in the chamber that caused the chambering and malfunction problems. As for the composite stock, well, mistakes happen.

I am not making excuses for the rifle, but in all fairness, SIG Sauer became one of the top firearms manufacturers by producing quality products. This was also an early production rifle and only a sample of one. When it did fire, the rifle shot MOA or better. I’m sure SIG will examine this rifle when I return it and find out what went wrong and how to improve it.

The SIG50 is available in states where the government is not afraid of its citizens. It is not available in California or Massachusetts.

SOURCES:

SIG Sauer Inc.
(603) 772-2302
www.sigsauer.com

Double Tap Ammunition
(866) 357-10MM
www.doubletapammo.com

Gunsite
(928) 636-4565
www.gunsite.com

Hornady Mfg. Co.
(800) 338-3220
www.hornady.com

Millett Sights
(913) 752-3400
www.millettsights.com

Summit Ammunition
(877) 726-4345
www.summitammunition.com

Warne Scope Mounts
(800) 683-5590
www.warnescopemounts.com

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