April 4th, 2015

Muzzle Threading — Don’t Remove Too Much Steel

Our friend Robert Whitley of ARX Enterprises LLC has learned, through careful measurement and testing, that some barrels threaded 5/8″ x 24 tpi at the muzzle may not deliver optimal accuracy. The reason is that the end of the barrel can bell out slightly, like a trombone, because too much steel has been removed. This is particularly true with .30-caliber barrels, but it can also be a problem with smaller caliber barrels (even 6mm). Robert demonstrates this phenomenon in the video below. All gunsmiths, and anyone considering threading a barrel, should watch the video. At 1:00 – 1:30 Robert gauges a 5/8″ x 24-threaded .30-Caliber barrel. You can see the belling effect clear as day.

Barrel Threading AR15 ARX Robert Whitley bartlein

“When setting up a commercial barrel in the lathe, we noticed that the maximum-sized bushing that would fit in the bore at the chamber end was almost .0015” smaller [than what would fit] at the muzzle. That precipitated my pin-gauging of a number of different commercial barrels that were threaded for 5/8” x 24 tpi. What I found is what’s shown on the video.” – R. Whitley

Solve Problem with a Larger Thread Diameter
If 5/8″ x 24 threading is potentially harmful to accuracy, is there a solution? Yes, you simply need to leave a little more steel on the barrel. (See Video starting at 02:40.) Frank Green of Bartlein barrels states: “We get these questions all the time. I say run the largest thread diameter that is possible.” Robert Whitley has found that a 3/4″ x 28 tpi threading does not cause the “belling effect”. Accordingly Robert recommends 3/4″ x 28 if you need to thread your barrel for a muzzle brake or suppressor. Robert explains: “We only make 3/4” x 28 tpi muzzle brakes and that’s what we recommend to customers.”

Barrel Threading AR15 ARX Robert Whitley bartlein

“See how much meatier the 3/4″ threading is vs. the 5/8″. The 3/4″ threading offers a lot more metal around the bore. There’s a lot less opportunity for the bore to become bell-mouthed…” – Robert Whitley

Barrel Threading Diameter — What’s Important to Know
By Robert Whitley
In truth, the 5/8” x 24 tpi threading never came out of any accuracy-based think tank or set-up, it’s a military .30-Cal threading for barrels that someone has to carry around (they needed to keep the barrel weight down so it was smaller in diameter and the threading had to work with that situation). People have somehow assumed because the military uses that threading for certain things that it must mean that it’s also fine for a highly accurate rifle too, but that’s not really correct.

I don’t think there is any better and realistic option than the 3/4” muzzle threading, and we also do it so there is no relief cut behind the threads on the barrel (i.e. put the relief cut on the brake or jam nut, don’t chop down on the muzzle of the barrel). For some reason many have a hard time grasping that the metal at the muzzle end of a rifle is “sacred” and you should not cut it down any more than absolutely necessary. A little threaded pencil diameter nub on the end of a barrel is not ideal for accuracy especially if it’s threaded and you need to torque on it. I cringe when I see a barrel with something like an MTU or Heavy Varmint contour, only to have an itty-bitty pencil thin threaded nub right at the muzzle so someone can “screw on a can” or a muzzle brake.

Lessons Learned Over the Years
A number of years ago I did a 30BR rifle project with Craig Kostyshyn who was big in the 30BR game and he made some of the best 30BR rifle barrels for benchrest competition. When I did the project I wanted a medium-heavy Palma type contour barrel I could use and also have a muzzle turndown for a front sight band. When he found out I was going to have the muzzle turned down he said “whoa, I need to provide for that when I make the barrel because if you turn the front down later you’ll be shooting a trombone” (i.e. the muzzle bore dimension would open up).

What he did was rough contour the barrel with the turndown (about .010” oversize) before he lapped the barrel, then when he lapped the barrel he took it easy in the muzzle area and worked the back of the barrel more. I thought he was a little bit excessive in his concerns but the barrel shot great and I wasn’t going to argue with him, after all he was shooting groups in the ones. I kind of just filed that away and never thought about it until recently when I went to have Fred from Sabreco do some chamber re-work on a commercial .30-caliber barrel I had. When setting up the barrel in the lathe and indicating things Fred noticed that the maximum-sized bushing that would fit in the bore at the chamber end was almost .0015” smaller [than what would fit] at the muzzle and he mentioned it to me. That precipitated my pin- gauging of a number of different commercial barrels I had that were threaded for 5/8” x 24 tpi. What I found is what’s shown on the video.

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April 4th, 2015

Registration Opens for 2015 CMP Events at Camp Perry

National Matches Camp Perry CMPThinking about going to Camp Perry this year? Well registration has opened for the 2015 CMP National Pistol and Rifle Matches. The National Matches at Camp Perry include the CMP National Trophy Rifle and Pistol Matches, the Pistol and Rifle Small Arms Firing Schools, CMP Games rifle events, and the NRA National Pistol, Smallbore Rifle, and High Power Rifle Championships. These matches are conducted jointly by the CMP, NRA, and the Ohio National Guard. Here are registration links for the CMP Trophy events for High Power Rifle, Rimfire Rifle, and Pistol. Note: You will have to register separately for the NRA Events.

2015 Nat’l Trophy Rifle Matches
(Online Registration)
Printable Rifle Entry Form

2015 Nat’l Rimfire Sporter Match
(Online Registration)
Printable Rimfire Entry Form

2015 Nat’l Trophy Pistol Matches
(Online Registration)
Printable Pistol Entry Form


2015 National Match Calendar

CLICK HERE to View/Download Calendar as Larger PDF File

CMP NRA National Match Calendar 2014 2015 Camp Perry Ohio

Simply click on the Calendar and it will zoom into a full-size PDF for easy viewing.
You can also download the PDF for printing.

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April 4th, 2015

Big Easter Sale on High-End Optics

Eurooptic.com sale

EuroOptic is running a big sale right now through April 12, 2015. You can save hundreds on riflescopes, LRFs, and binoculars from big-name companies such as Schmidt & Bender, Zeiss, Leica, and more. NOTE: If you call EuroOptic at (570) 368-3920, be sure to ask for Jason Baney and mention AccurateShooter.com. Jason will tell you about all the latest (and greatest) deals.

Here are some of the April Easter Specials available right now at EuroOptic.com:

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Eurooptic.com sale Eurooptic.com sale
Sale tip from EdLongrange. We welcome reader submissions.
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