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December 19th, 2021

Sunday GunDay: Flashy Chassis Showcase — Aluminum Wonders

1000-yard heavy gun chassis by Bruce Baer

For today’s Sunday GunDay story we showcase seven interesting metal-chassis rifles. While we love the look and feel of wood and fiberglass, metal does have its advantages. It can be crafted very straight and true, and the designs can achieve a very low center-of-gravity without sacrificing rigidity. In addition, a precisioned machined metal chassis tends to track extremely well.

Massive IBS Heavy Gun Milled from Solid Aluminum Billet

1000-yard heavy gun chassis by Bruce Baer

This remarkable 70-lb IBS Heavy Gun, was machined from solid aluminum billet, by Bruce Baer. It rests on a G&G Alvey rest split in the middle to comply with rules. This “heavy metal” CNC-machined wonder is a work of art designed for the 1000-yard game in the Heavy Gun class. Wood stocks, and to a lesser extent fiberglass stocks, are more forgiving, offering greater damping and recoil absorption. However, metal stocks offer superior rigidity, and the CNC machining allows tracking surfaces to be perfectly parallel.

Williamsport limits Heavy Guns to 100 pounds. Under IBS and NBRSA rules weight is unlimited. You will see a few massive 200-lb behemoths at IBS matches, but most competitors find that something in the 60-90 pound range works best. Bruce Baer explains, “You can’t stop a gun from recoiling. If it doesn’t recoil it will jump. If it jumps you might as well go home because you won’t shoot a good group. So it is pointless to try to build a gun so heavy as to eliminate all recoil. The more you restrict the rifle’s recoil the more temperamental that rifle will be. The 200-pounders just don’t out-perform something in the 60- to 80-pound range, and I think the optimal weight is 60-70 pounds.”

Bruce Baer likes the 70-lb overall weight for a heavy gun: “Extreme mass is not necessarily an advantage. Watch a locomotive starting up from zero–it will vibrate from one end to another. If the gun is too heavy I think it will vibrate at the start of recoil and that will kill accuracy. I want the gun to start from recoil with very little effort so it will be smooth from start to stop.”

Water-Cooled World Record-Setting Wondergun

joel pendergraft

We like “outside of the box” thinking. And in the world of competitive shooting, it can’t get more unconventional than this. But this radical liquid-cooled benchrest rig wasn’t just a crazy experiment — it actually delivered the goods. This IBS Heavy Gun, built by Joel Pendergraft, produced a superb 10-shot, 3.044″ group that stood as an International Benchrest Shooters (IBS) 1000-Yard Heavy Gun record for seven years, not being broken until 2016.

Joel Pendergraft

Using this water-cooled wondergun, Joel shot the record-breaking group in April 2009 at Hawks Ridge, NC. This monster features a .30-Caliber 12-twist, 4-groove Krieger barrel inside a water-filled sleeve (like on a liquid-cooled machine gun). Joel shot BIB 187gr flat-based bullets in Norma brass, pushed by a “generous amount” of Alliant Reloder 25 and Federal 210M primers. The cartridge was a big custom wildcat Joel listed as “.300 Ackley Improved”.

Pendergraft’s 3.044″ 10-shot group was a great feat, breaking one of the longest-standing, 1000-yard IBS World Records. And Joel’s 3.044″ record stood for 7 years!

Richard King’s Radical .223 Rem F-TR Skeleton Rifle

Richard King .223 Rem F-Class rig

Here’s something exotic from our Gun of the Week archives. We like this rig because it is so radical (we doubt that you have ever seen anything quite like it). Gun-builder Richard King calls this his “Texas-T”, noting that “this is my personal gun, built the way I wanted it. I know it’s radical and some may not care for it. But it works.” The rig was designed to shoot F-TR, but it can also be converted easily to shoot F-Open with a front rest.

Richard reports: “This is pretty much an all-aluminum rifle. The action is a Kelbly F-Class with a Shilen stainless steel competition trigger. The scope is a 1″-tube Leupold 36X with a Tucker Conversion set in Jewell spherical bearing rings. The .223 barrel is 30″ Pac-Nor 3-groove, 1:6.5″-twist mounted in a V-type barrel block. The bipod has vertical adjustment only via a dovetail slide activated by a stick handle. It works like a joy-stick, but for vertical only. I adjust for windage by moving the rear sandbag.”

Richard likes how the barrel block works: “With the barrel block forward, the vibrations should be at a low frequency. Instead of one long rod whipping, I now have two short rods (barrel halves) being dampened. This is my fourth barrel block gun. They work, but so does a good pillar-bedded action. [This rifle] is designed for my style of shooting. It is not meant to be a universal ‘fit all’ for the general public. However, I will say the design is adaptable. I can easily convert the system to run in F-Open Class. I would drop a big-bore barreled action into the V-block, slide on a heavier pre-zeroed scope and rings, add plates on the sides up front to bring the width to 3″, and maybe a recoil pad.”

F1 F-Open Chassis from Competition Machine

Eliseo competition machine F1 Aluminum F-Open Chassis

Along with his famed tube-guns, Gary Eliseo of Competition Machine has designed a modern, low-profile chassis system for F-Open competition. Assembled with Cerakoted aluminum beams, these F1 F-Open chassis systems offer great tracking with an ultra-low center of gravity.

Eliseo competition machine F1 Aluminum F-Open Chassis
Here is the F1 Chassis with “Marine Corps Red” powder coat finish. Read Full Report.

This F1 aluminum alloy chassis stock features a super-low center of gravity, plus adjustable length of pull, cheek rest, and drop. The stock is available in a wide choice of Cerakote finishes. The current Model F1 chassis features a action block mounting system to fit most actions. There was also an earlier version that had a free-floated action with the barrel in a barrel block, secured with epoxy. Both F1 versions (action block and barrel block) shot great, with excellent performances in competition.

Gen 1 F1 F-Open Chassis System with Barrel Block
Eliseo competition machine F1 Aluminum F-Open Chassis

State Championship Win with Home-Built Aluminum Stock

While most of the stocks featured above were crafted by professionals, the properties of aluminum allow it to be used by persons with some basic mechanical skills and metal-working tools. Here’s proof. Back in 2009, Forum Member John Dunbar (aka JD12) crafted his own aluminum F-Open stock. And he used that impressive metal stock to win the Wisconsin State F-Class championship. READ Full Story.

savage f-open aluminum stock

The stock for John’s “home-built” .284 Winchester was mated with a Savage target action. John designed and fabricated the aluminum stock himself. It features a central barrel block clamping a 32″ Brux barrel. Get this — John completed the rifle only 5 days before the match: “I finished machining/assembly on Monday night, did load workup Wednesday and Thursday nights, loaded rounds Friday night, and headed to Lodi at 4:30 on Saturday morning.” John even made his own co-axial front rest (see below)

John Dunbar

When Fiberglass Fails, Aluminum Stock Saves the Day

Australian Mark Fairbairn performed a “Quick Fix” during the 2018 Berger SW Nationals. Mark’s F-Open rifle, in a conventional fiberglass stock, was giving him random vertical during one yardage: “I had a bit of a problem with elevation — the stock was hitting somewhere [causing vertical]. I was X-X-X then a shot popped up in the 9 ring with no good reason. So I figured I better put a new stock on it. I got my old aluminium stock I brought from Australia and quickly adjusted it to fit on the Stolle.”

aluminum stock

Right on the firing line berm Mark swapped his barreled action into the metal stock of his own design. The clock was ticking… but the story had a happy ending. For the next yardage Mark shot a brilliant 150-7X, not dropping a point. So the “Quick Fix” did the trick. As they say Down Under — “Good on Ya, Mate!”

Home-Built Aluminum Chassis with Innovative A-Arm Bipod

Here is another home-built rig featuring an aluminum chassis mated to a Savage barreled action via a forward-mounted barrel block. This rig was crafted by Forum member Patrick Lundy, who followed the maxim: “If you can’t buy it, then build it.”

Lundy aluminum f-class rifle

Patrick Lundy was so impressed with a fellow shooter’s barrel-block rifle, that he build a similar match gun himself, complete with barrel block and aluminum chassis. Patrick was inspired by a metal stock belonging to Peter Gagne. But he added his own custom touches, including an innovative “A-Arm”-design bipod for shooting in F-TR class. The gun has been very successful in competition. READ FULL Report

Pat told us: “This new stock was a milestone in my shooting career — it was my very first attempt to build a stock. I wasn’t much of a wood worker but I did have a talent for building with metal. The stock was fabricated from 6061 T6 aluminum. With this gun I was able to shoot from a rest or a bipod.”

Lundy aluminum f-class rifle

Pat crafted the bipod from aluminum tubing: “The bipod was a very rigid A-frame design with welded aluminum tubing. I added slippery feet under the pod skis to facilitate smoother recoil. I realized that a wide-stance bipod had to recoil the same on both sides or the group would string horizontally.” Here is the innovative “A-Arm” bipod that Pat Lundy built for his rifle.

aluminum rifle bipod A-Arm homebuilt

Permalink - Articles, Competition, Gear Review, Gunsmithing No Comments »
April 5th, 2018

Old Meets New — Modern Modular Chassis for Swiss K31

Sureshot Armament group SAG K31 modular tactical chassis

You’ve never seen a Swiss K31 like this before…

The Sureshot Armament Group (SAG) has developed a modular aluminum chassis for the vintage, straight-pull Swiss K31 rifle. This chassis transforms an old classic into a modern, fast-cycling tactical rig. The SAG Lightweight K31 Rifle Chassis is CNC-Machined from aluminum. Hard anodized, it weighs just 2 lbs. 13 ounces. It offers adjustable cheek piece and butt-pad, with a three-inch LOP adjustment range. Believe it or not, installing a vintage K31 into this SAG stock is an easy bolt-on process. No modification of the K31 action is required.

The chassis-builder SAG states: “The main idea behind the SAG Lightweight K31 Rifle Chassis was to give the shooter …ergonomics of a Tube-gun but with lines of the classic rifle. The chassis ‘wraps’ the shooter around the rifle, moving bolt operation under the shooters cheek to allow the marksman to maintain cheek weld during the whole shooting series.” The chassis design also allows a more forward optics placement for better eye relief.

Sureshot Armament group SAG K31 modular tactical chassis

Sureshot Armament group SAG K31 modular tactical chassis

SAG Lightweight K31 Rifle Chassis Features:
CNC-Machined Aluminum with hard-anodized matte finish
Easy bolt-on installation to Swiss K31
Adjustable Cheek Piece (0-30mm)
Adjustable Buttpad to set LOP (11.5” – 14.5”)
KEYMOD Interface on fore-end and buttstock
Accepts any AR-type pistol grip
Overall chassis weight: 2 lbs. 13 oz. (1280 grams)
Chassis MSRP: €950 ($1163.00 USD)

Sureshot Armament group SAG K31 modular tactical chassis

About Switzerland’s Original Karabiner Model 1931 (K31)
The Karabiner Model 1931 (K31) is a magazine-fed, straight-pull bolt action rifle. It was the standard issue rifle of the Swiss armed forces from 1933 until 1958, though examples remained in service into the 1970s. It has a 6-round removable magazine, and is chambered for the 7.5×55mm Swiss Gewehrpatrone 1911 cartridge (aka GP 11).

Sureshot Armament group SAG K31 modular tactical chassis
Wiki Photo by Bouterolle, CC BY-SA 3.0

Although the K31 is a straight-pull carbine broadly based on previous Swiss “Schmidt–Rubin” service rifles and carbines, the K31 was not designed by Colonel Rudolf Schmidt (1832–1898) as he was not alive in 1931 to do so. Mechanical engineer Eduard Rubin (1846–1920) was the designer of the 7.5×55mm Swiss ammunition for which previous Swiss service rifles and the K31 are chambered. The Karabiner Model 1931 was a new design by the Eidgenössische Waffenfabrik in Bern, Switzerland under Colonel Adolf Furrer (1873–1958). The Karabiner Model 1931 replaced both the Model 1911 rifle and carbine and was gradually replaced by the Stgw 57 from 1958 onwards.

Permalink Gunsmithing, New Product, Tactical 11 Comments »
January 3rd, 2017

New Bergara B14 HMR Rifle in 6.5 Creedmoor and .308 Win

Bergara HMR rifle PRS production class 6.5 Creedmoor .308 Winchester

Bergera Rifles has introduced a new rifle designed for the tactical, PRS, and long-range hunting markets. Bergara’s new B14 Series Hunting and Match Rifle (HMR) features an ergonomic, adjustable stock fitted with an internal aluminum sub-chassis. Initially, the HMR will be offered in 6.5 Creedmoor and .308 Win chamberings, fed with AICS-compatible box magazines. We’re pleased that all HMRs are guaranteed to produce sub-MOA groups at 100 yards using factory match-grade ammunition. Weight, without optics, is 9.15 lbs, about one pound less than the Ruger Precision Rifle. MSRP is $1,150.00.

The Spanish-made HMR boasts a molded synthetic stock with built-in machined aluminum mini-chassis. This mini-chassis allows secure, repeatable bedding for Bergara’s B14 action, which features two-lug bolt wtih coned bolt-head. The Chrome-Moly Bergara barrels are threaded 5/8″ x 24 at the muzzle for brakes or suppressors. The HMR uses a precision-machined bottom metal and is designed to accept AICS-style magazines.

Bergara HMR rifle PRS production class 6.5 Creedmoor .308 Winchester

The stock has a multi-stage textured finish, which looks good. Designed for both righties and lefties, the ambidextrous stock features an adjustable cheekpiece, and length of pull is adjustable with simple spacers. For slings and accessories, the HMR stock offers multiple flush cup QD mounts as well as multiple swivel studs for bipods and/or slings.

Bergara HMR rifle PRS production class 6.5 Creedmoor .308 Winchester

This should be an interesting addition to the line-up of factory rifles suitable for the PRS Series Production Class. But frankly, we think Bergara went too short with the barrels (or at least should offer longer barrels as options). In 6.5 Creedmoor, at 22″ you’re giving up 90 FPS or so compared to a 27″ (See Barrel Cut-Down Test). Additionally, we think most PRS competitors would prefer a different profile on the fore-end. Nonetheless for tactical guys who don’t like modular metal stocks, this is an interesting (and pretty affordable) new offering.

Bergara B14 HMR Rifle Specifications:

Chamberings: 6.5 Creedmoor and .308 Winchester
Action Type: 2-lug action, sliding plate extractor, cone bolt nose and breech
Magazine: AICS style mag compatible – Includes one Magpul® PMAG AICS Magazine
Barrel Specs: 6.5 Creedmoor (1:8″ Twist, 22″); .308 Win (1:10″ twist; 20″)
Mini-Chassis Material: 7075 T6 aluminum
Weight without scope: 9.15 pounds
MSRP: $1,150.00

Learn more about Bergara rifles in this SHOT Show Video by the 6.5 Guys

Permalink New Product, Tactical 4 Comments »