March 28th, 2015

How It Works: Cut-Away Winchester Pump-Action Shotgun

Model 12 function shotgun cutaway see-through cut-away larry potterfield

Even wonder how a pump shotgun works? Then watch this fascinating video from MidwayUSA. The operation of a pump-action shotgun is illustrated with a special cut-away version of a Winchester Model 12. The shotgun has been modified to reveal the inner workings. This cut-away Model 12 still loads and ejects dummy shells, but you can see how the lugs, slides, locks, ramps, springs and other internal parts work. You’ll be amazed how complicated this old pump-gun is. (The Model 12, Winchester’s first hammerless shotgun, is one of the most popular scatterguns ever made. Over 2,000,000 were sold.)

Skip Ahead to 3:00 to See Cut-Away in Action

To see how the Model 12 works, you can skip forward to the 3:00 minute mark in the video. The first part of the video shows how the Model 12 was “sliced and diced” to expose the inner workings. Larry Potterfield of MidwayUSA explains that “the factories often used cut-aways as sales tools to show how a specific model operated”. In addition the U.S. Military used cut-aways for training purposes.

Here is the cut-away completed. Even the pump grip has been sliced to reveal the inner workings.
Model 12 function shotgun cutaway see-through cut-away larry potterfield

Here’s a close-up, showing how the bolt retracts to eject a round.
Model 12 function shotgun cutaway see-through cut-away larry potterfield

A round has been picked up from the feed tube, and then is lifted into the chamber.
Model 12 function shotgun cutaway see-through cut-away larry potterfield

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March 20th, 2015

Left-Port, Side-Charging AR Upper — Not Just for Southpaws

Here’s something you may not have seen before — a left-port, side-charging AR15 Upper. This unit was developed by John Scandale of Keystone Accuracy. While this was designed for left-handed High Power shooters, the lefty upper also works well for right-handed F-TR shooters. This design allows a prone shooter to single-load with his left hand, an efficient system for a right-handed shooter. Here is a review of the lefty upper from German Salazar’s Rifleman’s Journal website. Like John Scandale, German is a southpaw.

The Lefty AR Upper from Keystone Accuracy

by German Salazar, RiflemansJournal.com
We left-handed shooters are always the last to get the benefit of new firearms developments, or so it seems to us most of the time. There is no rifle more popular today than the AR15, whether for competitive shooting or plain recreational use; but even for that ubiquitous black rifle, left-handed items are few and far between. However, Keystone Accuracy run by left-handed High Power shooter John Scandale has some good stuff for us.

Left-handed Left AR15 Upper German Salazar Keystone Accuracy  Scandale

left hand ar15 upper keystone accuracy

John is a long time High Power shooter, a member of the National Guard’s All-Guard rifle team and a Distinguished Rifleman. He knows exactly what makes a good High Power rifle — unlike many of the mail-order parts and pieces you see offered for sale by someone who only shoots his computer keyboard… John is a real shooter, I’ve known him for many years and trust his work.

The most interesting item from Keystone is the left-hand billet upper receiver for the AR15 match rifle. This thick-wall, CNC-machined piece appears to be very durable and fits all existing AR15 lower receivers.

left handed billet ar-15 ar15 upper side port

When the AR15 was becoming popular in High Power shooting in the mid-1990s, I had a match rifle built on one. To solve the left-hand problem, I had a second port milled into the left side to allow me to load the rifle comfortably in slow-fire, single-load matches. Unfortunately, sometimes the round I flicked into the left port would fall right out of the right port! That was a bit frustrating and this receiver, along with an appropriate left-handed bolt assembly will work for the lefty just as we desire.

left-handed ar15 upper

I’ve seen quite a few AR15 based rifles in F-TR at our local club matches over the past year. This upper would be a good choice for many right-handed shooters using the AR for F-Class as it allows loading with the left hand while the right hand remains on the pistol grip and ready to fire when the target appears. In light of the fact that the bolt release is on the left side, that makes life a lot simpler than using the right hand! So if you’re a left-handed shooter or even a right-handed F-Class shooter, give this some thought, it might be just what you’ve been waiting for and didn’t even know it!

Permalink Gunsmithing, New Product 2 Comments »
March 16th, 2015

Blaser Bling! R8 Serial Number 100,000 Showcased at IWA

In a corner of the Blaser booth at the IWA show in Germany was a very special rifle — Blaser R8 Serial Number 100,000. This one-of-a-kind Blaser is blinged to the max, befitting its milestone status as the 100,000th R8. “Designed without compromise” this rifle features mind-blowing wood, and elaborate engraving. It is highly decorated with images of the Argali, a type of big-horned sheep.

CLICK Photo to See Large, Full-Screen Image (More Detail)
Blaser R8 Showpiece Gun rifle engraving

What’s in a number? Blaser tell us: “In serial number 100,000… Nothing short of perfection would be acceptable from the masters of wood and steel. Two internationally recognized artists were selected, each working in their unique mediums. Painter Rudi Kohl has drafted, in his signature style, a painstaking depiction of Argali, the king of wild sheep, in their natural habitat. Engraver Jürgen Göser was then responsible for implementation of the drafts. The master engraver went about his task in his usual manner, meticulously and with absolute attention to detail.” Skeletonized octagonal pistol grip cap and steel butt plate, inlayed with ebony, were then added to complete the frame.

This R8 has some interesting hardware. The barrel is a fluted octagonal tube, the first of its kind on a Blaser R8. Front and rear sights were custom-machined from billet to blend with the silhouette of the rifle. Both receiver and bolt housing were shaped and polished by hand.

Story Tip from EdLongrange. We welcome reader submissions.
Permalink Gunsmithing, Hunting/Varminting No Comments »
March 10th, 2015

Run AR Magazines in your Rem 700 Bolt Gun

Pacific tool and gauge ar-15 magazine bottom metalHow’d you like to run AR-15 Mags in your Rem 700 bolt gun? Sound far-fetched? Well think again. Pacific Tool and Gauge has developed a unique bottom metal system for Rem 700 short actions that works with standard AR-15 mags, providing reliable function with .223 Rem (5.56x45mm) rounds. The AR-mag compatible Rem 700 Bottom Metal costs $129.00 by itself, or $149.00 with a C-Products 10-round magazine.

The system works with straight 5-round, 10-round, and 20-round metal mags as well as larger, angled 30-round metal mags. (Because they are thicker, Magpul mags and other polymer magazines do not work with this PT&G bottom metal system.)

Pacific tool Gauge Rem 700 bottom metal ar15 ar-15 magpul magazine

At SHOT Show, Dave Kiff showed us the AR-Mag compatible bottom metal. “It took a lot of time to get the geometry just right, but we’re proud of this product”, Dave said. A PT&G exclusive, this special bottom metal as been designed to fit in all Remington 700 standard factory stocks right off the shelf with minimal inletting. This bottom metal features a handy mag release button incorporated into the side of the bottom metal (this is more reliable and secure than a mag release in the trigger guard).

Pacific tool Gauge Rem 700 bottom metal ar15 ar-15 magpul magazine

Slight Modification Required During Installation
Customers purchasing this bottom metal will need to modify their Rem 700 actions very slightly, to create a little extra clearance. The Feed Bevel (left photo) needs to be opened to 0.660″, while the mag well needs to be opened to 0.900″.

Pacific tool Gauge Rem 700 bottom metal ar15 ar-15 magpul magazine

Product tip from EdLongrange. We welcome reader submissions.
Permalink Gunsmithing, New Product 3 Comments »
March 7th, 2015

Gunsmithing: Installing a Picatinny Rail

In the video below, Forum Member Thomas Haugland (from Norway) shows how to install a Picatinny-type rail on a Sako action. Every stage of the process is illustrated — removing the barrel from the action, drilling/tapping the action, aligning/attaching the rail, and finally mounting the scope and test-firing the rifle. Note that the action is removed using a large adjustable-end wrench with brass disks to protect the finish. This is possible because this particular Sako action has a flat bottom and top. With a different action you’ll want to use a custom action wrench.

In the video, Thomas and his assistant actually fabricate the rail from scratch. That’s probably beyond the ability of most do-it-yourselfers. You can purchase precisely machined Picatinnny rails from Seekins Precision and other sources instead. Still, it is interesting to see the milling of the rail. Note that, before screwing the rail to the top of the action, Thomas applies a marine epoxy (timeline 3:18). This effectively beds the rail to the top of the action and provides a more secure installation.

You can find more interesting gunsmithing, hunting, and long-range shooting videos on Thomas Haugland’s YouTube Channel.

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March 3rd, 2015

AR-15 Bolt Sheds Lugs — Can You Figure Out What Happened?

AR15 AR-15 Bolt lug shear damage Kaboom gas system pressure

Black Rifle Gone Bad…
Take a close look at this AR-15 bolt. Notice something missing — namely all the lugs? A healthy AR-15 bolt has seven (7) bearing lugs (plus an extractor hump). For all seven lugs to have sheared “clean off”, something serious must have happened to this bolt assembly. The folks at Brownells published this “lost luggage” image on Facebook to spur discussion. So, you AR experts out there — what do you think caused the problem here? Was it over-pressure, metal defect, headspace problem, gas system malfunction (or some combination of issues)? Post your theories in the comment section below…

AR15 AR-15 Bolt lug shear damage Kaboom gas system pressure

Permalink Gunsmithing 59 Comments »
March 1st, 2015

Surprising Results in .223 Rem Barrel Cut-Down Velocity Test

With barrels, one always wonders “Can a little more length provide a meaningful velocity gain?” To help answer that question, Rifleshooter.com performed an interesting test, cutting the barrel of a .223 Rem rifle from 26″ all the way down to 16.5″. The cuts were made in one-inch intervals with a rotary saw. At each cut length, velocity was measured with a Magnetospeed chronograph. To make the test even more interesting, four different types of .223 Rem/5.56 ammo were chron’d at each barrel length.

.223 Rem Cut-Down Test barrel UMC m855

READ RifleShooter.com 5.56/.223 Barrel Cut-Down Test Article.

Test Barrel Lost 25.34 FPS Per Inch (.223 Rem Chambering)
How much velocity do you think was lost, on average, for each 1″ reduction in barrel length? The answer may surprise you. The average speed loss of the four types of .223/5.56 ammo, with a 9.5″ shortening of barrel length, was 240.75 fps total (from start to finish). That works out to an average loss of 25.34 fps per inch. (See inch-by-inch data HERE.)

5.56/.223 Barrel Cut-Down Speed Test 26″ to 16.5″ Start FPS at 26″ End FPS at 16.5″ Total Loss Average Loss Per Inch
UMC .223 55gr 3182* 2968 214 22.5 FPS
Federal M193 55gr 3431 3187 244 25.7 FPS
Win m855 62gr 3280 2992 288 30.3 FPS
Blk Hills .223 68gr 2849 2632 217 22.8 FPS

*There may have been an error. The 25″ velocity was higher at 3221 fps.

Rifleshooter.com observed: “Cutting the barrel from 26″ to 16.5″ resulted in a velocity reduction of 214 ft/sec with the UMC 223 55-grain cartridge, 244 ft/sec with the Federal M-193 cartridge, 288 ft/sec with the Winchester M855 cartridge and 217 ft/sec with the Back Hills 223 68-grain match cartridge.”

How the Test Was Done
The testers described their procedure as follows: “Ballistic data was gathered using a Magnetospeed barrel-mounted ballistic chronograph. At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition. Average velocity and standard deviation were logged for each round. Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. The barrel was cut off using a cold saw. The test protocol was repeated for the next length. Temperature was 45.7° F.”

CLICK HERE to Read the Rifleshooter.com Test. This includes detailed charts with inch-by-inch velocity numbers.

Much Different Results with 6mmBR and a Longer Barrel
The results from Rifleshooter.com’s .223/5.56 test are quite different than the results we recorded some years ago with a barrel chambered for the 6mmBR cartridge. When we cut our 6mmBR barrel down from 33″ to 28″ we only lost about 8 FPS per inch. Obviously this is a different cartridge type, but also our 6mmBR barrel end length was longer than Rifleshooter.com’s .223 Rem start length. Velocity loss may be more extreme with shorter barrel lengths.

Permalink Gunsmithing, Tech Tip 6 Comments »
March 1st, 2015

Offset Scope Mount Helps Shooter with Vision Problem

offset scope base mountForum member Roy Bertalotto did a real nice off-set scope installation on a bolt gun to help a sight-challenged shooter. Roy explains: “A friend of mine shoots left-handed and has lost the sight in his left eye. I built him a scope mount so he can still shoot left-handed, but now use his right eye.” Roy’s fabrication work is impressive and we praise his efforts to help a fellow shooter stay in the game.

Roy bolted a plate to the existing scope rail on the top centerline of the Rem 700 action. This plate extends a few inches to the right. On the outboard end of the plate, Roy fitted a second scope rail, aligned with the bore. Weaver-based rings are then clamped to the outboard (right side) auxiliary rail.

offset scope base mount

offset scope base mount

offset scope base mount

Be Careful of Canting Issues with Offset Scope Installations
We’re pleased to see that Roy developed a solution for a shooter with an optical disability, but we want to stress that this is a specialized installation that can create some problems with point of impact shift if the gun is not maintained perfectly level. With the amount of horizontal offset (between the scope’s optical axis and the bore axis) built into this rig, if the rifle is canted, point of impact can shift rather dramatically. For a southpaw who is willing to adapt his/her shooting style, it may be better, in the long run, to learn to shoot right-handed if his/her right eye is the only good eye. Likewise, if a right-handed shooter can only see well through his left eye, he may benefit from learning how to hold the stock and work the trigger with his left hand. The shooter could still work the bolt with his non-trigger hand. Changing from right-hand to left-hand shooting (or vice-versa) may require a stock swap if the stock is not ambidextrous.

Permalink Gunsmithing 2 Comments »
February 24th, 2015

Tech Trends: Precision Barrel Bore-Honing

Some custom barrel makers are now honing barrels (after drilling) to improve bore diameter uniformity, smooth the interior finish, and reduce barrel lapping times. For years, large-scale manufacturers of hammer-forged barrels have employed honing. Now the process is being used by smaller, “boutique” barrel-makers. This article explains how and why barrel honing is done. Take the time to watch the video. For anyone with an interest in barrel-making, this video is an eye-opener…

Barrel Honing Process Demonstrated (Worth Watching!):

Barrel Bore honing cut-rifled rifling hammer forging accurateshooter.com

For custom barrel makers, honing is a time-saver and cost cutter. A few minutes on a honing machine can cut lapping times in half, leaving a cross-hatched surface finish in single or low double-digit Ra. Honing is the same process used to make diesel fuel injectors with bore roundness and straightness controlled to fractions of a micron (<0.000040"), with surface finish Ra ≤0.15 µm (6 µin).

A key manufacturing process used for hammer-forged barrels is now getting attention from the makers of custom button-rifled barrels. This process is precision bore-honing. Honing produces a high-quality bore surface fast, which is critical to hammer forging. (Why is honing so important with hammer forging? Surface finish is the one feature of the barrel that cannot be controlled in hammer forging. Surface imperfections in a barrel blank tend to be amplified as the blank is formed on the rifling mandrel. And if the bore is chromed afterwards, imperfections in the surface finish become even more obvious.)

Honing dramatically improves bore diameter size uniformity and accuracy, surface finish and roundness throughout the length of the barrel. It can certainly be used in place of a pre-rifling lap. The chief difference between a lapped and honed bore is the direction of the finish lines in the bore. Honing leaves fine spiraling crosshatch lines, while a lap leaves lines going longitudinally in the bore. After rifling the manufacturer can remove the crosshatch finish with a quick lap if desired. Honing is fast, accurate, and can be automated. Its surface quality and geometry can duplicate lapping, except for the longitudinal lines of the lapped finish.

Barrel Bore honing cut-rifled rifling hammer forging accurateshooter.com

Frank Green of Bartlein Barrels told us: “We worked with Sunnen and we did all the initial testing on the prototype machine for them. The machine works great! We ordered and received last year a new manufactured machine with the changes we wanted on it and we just ordered a second one a month or so ago. Should be here next month.”

Computer-Controlled Bore-Honing
Honing can be done with great precision through the use of advanced, computer-controlled honing machines. Sunnen Products Company recently introduced a new machine for .17 to .50-caliber barrels (see control panel below). The spindles on this machine can correct bore size imperfections so small only an air gauge can measure them. The consistency this allows improves bore uniformity, which, in turn, produces more accurate barrels for the precision market.

Barrel Bore honing cut-rifled rifling hammer forging accurateshooter.com

Barrel Bore honing cut-rifled rifling hammer forging accurateshooter.com

Sunnen Products Company is the world’s largest vertically-integrated manufacturer of honing systems, tooling, abrasives, coolants and gauging for precision bore-sizing and finishing. Sunnen’s customers include manufacturers of diesel and gas engines, aerospace components, hydraulic components, oil field equipment, and gun/cannon barrels. Sunnen, which just celebrated its 90th anniversary, employs more than 600 people worldwide.

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February 17th, 2015

Is “Stainless Steel” Really Rust-Proof?

Some folks feel that they don’t have to worry about rust and corrosion on stainless steel barrels, actions, and other components. That’s not really true. “Stainless” is a bit of a misnomer. First, there are different types of stainless steel alloys, with different degrees of rust resistance. 300 series stainless is more corrosion resistant than the 416 stainless commonly used in barrels. The composition (by percentage weight) of 416 stainless is 0.15% carbon, 12-14% chromium and the rest iron. 416 stainless steel lacks the roughly 10% nickel content that makes the 300 series more corrosion resistant in atmospheric conditions. But because 416 handles pressure better and is easier to machine (than 300 series steel), 416 stainless remains the better choice for barrels.

stainless steel barrel Techshooter

Though some grades of stainless are more corrosion-resistent, ALL varieties of stainless steel can rust if they are not handled and stored properly. Forum reader Kells81 observed: “Wanna see some rusted stainless? Go to the big “C” brand store in Ft. Worth. Every stainless gun they have on the used gun rack is rusted.” Tom Easly of TRE Custom explains: “Sweat is very corrosive. Sweat and blood will rust many stainless steels. I hate to handle my guns or drip on them when I sweat. It really helps to just wipe them good with a wet rag, dry and wipe on a light coating of gun oil. I think most stainless barrels are made from type 416 stainless, and it is generally pretty corrosion resistant, but not when exposed to sweat, blood, or chlorates (corrosive priming), and some other electrolytes.”

Forum member Jacob, who is studying materials science at LSU, provides this technical information: “The basic resistance of stainless steel occurs because of its ability to form a protective coating on the metal surface. This coating is a ‘passive’ film which resists further ‘oxidation’ or rusting. The formation of this film is instantaneous in an oxidizing atmosphere such as air, water, or other fluids that contain oxygen. Once the layer has formed, we say that the metal has become ‘passivated’ and the oxidation or ‘rusting’ rate will slow down to less than 0.002″ per year (0.05 mm per year).

Unlike aluminum or silver, this passive film is invisible in stainless steel. It’s created when oxygen combines with the chrome in the stainless to form chrome oxide which is more commonly called ‘ceramic’. This protective oxide or ceramic coating is common to most corrosion resistant materials.

Halogen salts, especially chlorides, easily penetrate this passive film and will allow corrosive attack to occur. The halogens are easy to recognize because they end in the letters ‘ine’. Listed in order of their activity they are: fluorine, chlorine, bromine, iodine, astatine.

These are the same chemicals that will penetrate Teflon and cause trouble with Teflon coated or encapsulated o-rings and/ or similar coated materials. Chlorides are one of the most common elements in nature and if that isn’t bad enough, they’re also soluble, active ions. These provide the basis for electrolytes. The presence of electrolytic solutions can accelerate corrosion or chemical attack.”

CONCLUSION: Stainless steel barrels and components won’t rust nearly as fast as blued steel, but you still have to take precautions — particularly removing sweat and corrosive salts from the barrel. Also, don’t let moisture build up inside or outside of the barrel. We recommend wiping your barrels and actions with Eezox, or Corrosion-X after each use. These are both extremely effective rust-fighters that go on thin, without leaving a greasy residue. (Eezox leaves a clear finish, while Corrosion-X has a slightly waxy finish.) Also store your guns in Bore-Store bags when the guns go in the safe. Bore-Stores wick away moisture, and the synthetic fleece inner surface is treated with rust-fighting chemicals. Bore-Stores also protect your guns against dings and scratches. To discuss how rust can form on stainless steel, visit this FORUM Thread.

Permalink Gunsmithing 12 Comments »
February 5th, 2015

U.S. F-Open Team Hardware Choices

Are you trying to decide what components to use for your next F-Class build, or are you looking to upgrade your current rig? Wonder what the “big dogs” in the sport have selected as their hardware? Here’s what United States F-Open team members are using. The most popular chambering is the .284 Winchester, followed by the 7mm Walker (a 40° .284 Winchester Improved). Kelbly and BAT actions are the most popular, and nearly all team members are using cut-rifled barrels. A wide variety of stocks are used, with PR&T holding a slight edge over second-place McMillan.

F-Class Team USA F-Open

Click Image Below for Larger Version:

F-Class Team USA F-Open

Story Tip from Dominion of Canada Rifle Association.

Permalink Competition, Gunsmithing 11 Comments »
January 25th, 2015

Cortina’s Corner: Installing Jewell Trigger in Panda F-Class Action

Eric Cortina Lapua Jewell Trigger Panda Stolle Action Kelbly Kelbly's

In the video below, Forum member Eric Cortina shows how to install a Jewell Benchrest trigger into a Kelbly F-Class Panda action. You could follow the same simple procedure to install a Jewell in a standard Panda action. Kelbly’s sell both standard and long versions of the F-Class Panda action. Both versions feature integral recoil lugs in the front.

To see more detail in this “how-to” video, you can zoom it to full-screen size. Simply click the full-screen icon (4-cornered frame) just to the right of the YouTube logo in the lower right.

Eric Cortina Lapua Jewell Trigger Panda Stolle Action Kelbly Kelbly's

Eric Cortina Lapua Jewell Trigger Panda Stolle Action Kelbly Kelbly's

Permalink Gunsmithing, Tech Tip 1 Comment »