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 24th, 2015

NSSF Urges Public to Oppose ATF Ban on 5.56 M855 Ammo

BATFE ATF logoThe Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is seeking to ban commonly-used 5.56 M855 “green tip” ball ammunition as “armor piercing ammunition” and is seeking public comment on the proposal. The National Shooting Sports Foundation (NSSF) urges target shooters and gun owners to contact ATF to oppose this proposed ban.

For decades, under the “sporting purposes” doctrine, commonly-available “green tip” M855 and SS109 rifle ammunition has been exempt from federal law banning armor-piercing ammunition. There is no question that this 5.56 ball ammo has been widely used by law-abiding American citizens for sporting purposes.

Winchester-brand 5.56X45 62gr NATO M855 FMJ Ammunition
m855 Olin winchester ball SS109 Brownells accurateshooter.com

NSSF SS109 M855 .223 Rem 5.56x45mm ammo ammunition penetratorThe NSSF has an online form that makes it easy to voice your opinion on the proposed ban on 5.56 ball ammo. This form will direct your comments to Congress and/or the ATF. Click the button at right to navigate to the NSSF online form.

Commentary by Jim Shepherd, The Shooting Wire
Should the ATF reclassify surplus (and widely used) M855 and SS109 ammunition as armor-piercing, it would then be illegal for consumer consumption. This weekend, we received word that apparently many gun owners didn’t find this to be a compelling reason to record their objections with the federal government. With only a few days remaining in the ATF’s solicitation of comments, fewer than 6,000 shooters have registered their displeasure with the proposal.That, as one of my least-favorite instructors used to say, is simply unacceptable.”

Permalink Bullets, Brass, Ammo, News 2 Comments »
February 24th, 2015

For the Man Who Has Everything — Lapua 9mm Brass

Here’s something you don’t see every day — pistol-caliber Lapua brass. We shoot superior Lapua brass in our rifles, and now you can get the “good stuff” for your 9mm pistols too. It’s nice to know that Lapua 9mm brass is available for those guys who accept “nothing but the best”. Grafs.com received a special order of 9mm Luger (aka 9x19mm or 9mm NATO) pistol brass made by Lapua. It is available right now for $19.99 per 100-count bag or $179.99 per 1000-count box. That’s 38% off the regular 1K box price.

Smith Wesson 929 9mm revolver miculek

When It Pays to Shoot Premium Pistol Brass
Is this Lapua 9mm brass worth the price compared to the cheaper alternatives (such as once-fired police range pickups)? We think the answer depends on your application. If you shoot a 9mm pistol in Bullseye competition, yes it makes sense to get the Lapua. Or, if you have a 9mm revolver that carries the shells in a moon clip, the Lapua brass may be worth getting. With a 9mm revolver, your brass is not marred by an extractor claw and then ejected on to the ground. If we had the impressive new 8-shot, Miculek Edition Smith & Wesson model 929 9mm revolver (below), we’d definitely shoot Lapua brass.

Smith Wesson 929 9mm revolver miculek

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