August 25th, 2014

AR Ejector Mod For Improved Reliability with Larger Cartridges

TECH TIP by Robert Whitley, AR-X Enterprises LLC
Over the years, while working with various AR-15 cartridges that require a larger bolt-face bolt (i.e. bigger than a 5.56 NATO/.223 Rem bolt-face, like those cartridges that use a 6.8 SPC bolt or the bolt face suitable for the 6.5 Grendel-based cartridges), I have found that there is an increased potential for a certain type of jam if a modification to the standard “Mil-Spec”, square-edged ejector is not made.

The original AR-15 square-edged ejector design was made for a much smaller-diameter bolt face and the smaller diameter 5.56 NATO/.223 Rem case, and it works perfectly in that application. However, as people have adapted the AR-15 platform to shoot bigger cartridges, some parts have been modified to accept the larger cartridges (i.e. bigger bolt-face bolts for the 6.8 SPC and the 6.5 Grendel, and different extractors), yet other parts have been all but ignored. One of these “ignored” parts has been the ejector. Most of the larger-bolt-face AR-15 bolts still use the standard “Mil-Spec”, square-edged 5.56 NATO/.223 Rem. ejector. That’s the problem. But there is a simple, reliable fix!

Robert Whitley AR-X Enterprises AR AR15 Bolt jam fix ejector mod

Chamfering AR Ejector for Improved Reliablity with 6mm, 6.5mm and 6.8mm Cartridges
With the larger bolt face and the larger-diameter AR cases, the old-style “Mil-Spec” ejector can cause infrequent but still annoying jams if the ejector is not modified. The jam can occur when a cartridge case feeds up and out of the right side of the magazine, and as it does so, the back of the case must slide across the bolt face and sideways over top of the ejector if it is to center up to the chamber and feed in. If the side of the case catches on the sharp-edged ejector you can get a jam. (See picture above).

Fortunately there is an easy fix for this. One way is to take the ejector out and spin it in a lathe or cordless drill and machine or grind it and round or chamfer the sharp edge. (See picture of rounded ejector next to square edged ejector).

Robert Whitley AR-X Enterprises AR AR15 Bolt jam fix ejector mod

Quick Fix Alternative — Bevel Your Ejector
Another “quick fix” is to leave the ejector in the bolt and chamfer the sharp edge with something like a Dremel tool. (See picture). This fix is easy to do and permanently resolves this potential feeding jam issue. There are no downsides to this modification if done right and I would recommend this modification for the ejectors in all larger bolt-face AR-15 bolts.

Robert Whitley AR-X Enterprises AR AR15 Bolt jam fix ejector mod

Robert Whitley AR-X Enterprises AR AR15 Bolt jam fix ejector mod

This gunsmithing tip provided by Robert Whitley of AR-X Enterprises LLC, 199 North Broad Street, Doylestown, PA 18901. Phone: (215) 348-8789. Website: 6mmAR.com.

Permalink Gunsmithing, Tech Tip 4 Comments »
February 8th, 2012

Hornady 6.5 Grendel Brass — Whitley Reports

Robert Whitley of AR-X Enterprises, LLC builds match-grade uppers for AR-platform rifles. Many of Robert’s favorite chamberings are based on the 6.5 Grendel case necked-down to 6mm. Until 2011, Lapua was the only source for 6.5 Grendel brass. As you’d expect, Lapua’s Grendel brass is truly excellent, but it is also pricey, and sometimes hard to find. Now Hornady is producing USA-made 6.5 Grendel brass. Robert Whitley has worked with the Hornady 6.5 Grendel brass for over a year now and he is able to assess its performance compared to the original Lapua version. Writing in our Shooters’ Forum, Robert reveals: “It’s decent brass but hot loads will loosen the primer pockets fast. With moderate loads you will get good case life and service from the brass and it can deliver excellent accuracy as well. Not Lapua but not bad either.”

Robert reports: “I was able to get my hands on some of Hornady’s 6.5 Grendel brass. My big question was how it would measure up, particularly the loaded necks, and whether it would be compatible with our existing 6mmAR and Turbo 40 die sets. As it turns out, this brass looks like a perfect fit for our existing die sets (and obviously 6.5 Grendel die sets too). Accordingly, folks with existing die sets will be able to use the Hornady brass without any issues.” However, as the loaded neck on the Hornady brass is .001″ (one-thousandth) slimmer than Lapua brass, you may want to try a smaller bushing when sizing Hornady Grendel brass.

Hornady 6.5 Grendel brass

The Hornady 6.5 Grendel brass has a LARGE Flash Hole, about .078″ versus .0591″ for Lapua brass. Dimensionally, the biggest difference is the shoulder diameter, with the Hornady brass measuring 0.428″ vs. 0.424″ for the Lapua brass. The Hornady is actually a better fit for 6mmAR chambers which are about 0.432″ at the shoulder. Interestingly, case H20 capacity is virtually identical. Water capacity of new, unfired Hornady 6.5 Grendel brass is 35.1 grains, while new, unfired Lapua Grendel brass holds 35.0 grains of H20. Both brands of Grendel brass increase to about 36.0 grains H20 capacity after firing and full-length sizing.

Here are some of the particulars of the Hornady cases:

Hornady 6.5 Grendel Brass Lapua 6.5 Grendel Brass
Flash hole diameter: ~ .078″
OAL of brass: Average 1.515″
Weight of cases: 111.7 to 113.0 grains
Web diameter, unfired: 0.4375″
Shoulder diameter, unfired: 0.428″
Loaded neck diameter: 0.2895″
6mmAR loaded neck: 0.270″
Flash hole diameter: 1.5mm (0.0591″)
OAL of brass: Average 1.515″
Weight of cases: 111.0 to 112.5 grains
Web diameter, unfired: 0.4385″
Shoulder diameter, unfired: 0.424″
Loaded neck diameter: 0.290″
6mmAR loaded neck: 0.271″
Permalink Bullets, Brass, Ammo, New Product, Reloading 12 Comments »
June 7th, 2011

The 6mm BRX — Myth-Busting with Bob Crone

Bob Crone 6mm BRXDispelling Some 6mm BRX Myths, by Robert Whitley
I recently had an interesting and fact-filled conversation with Bob Crone (the inventor of the 6mm BRX) about his BRX. Bob actually called me because he was concerned that there are a lot of myths and about his 6mm BRX and he wanted to “set the record straight” on a few things. Here’s my summary of some topics we discussed:

Myth One: Bob made his 6mm BRX chamber by running a 6mm BR reamer in too deep.

Truth: There is no truth to Myth One. Bob said he specifically designed the BRX reamer and had it made with the head space he specified and a neck length appropriate for his newly designed 6mm BRX wildcat cartridge.

Myth Two: In the course of making up his 6mm BRX, Bob had a version with a .120″ longer head space than a 6mm BR Norma.

Bob Crone 6mm BRXTruth: Bob was clear that his original design for the 6mm BRX always had a .100″ longer head space than a 6mm BR and that he never deviated from that. Right after Bob started working with his 6mm BRX, Bill Shehane came forward with a 6mm BRX version he made up that had a .120″ longer head space, and thus the confusion started. In truth, the original 6mm BRX always was (and still is) a chambering with a head space .100″ longer than a 6mm BR Norma.

Myth Three: The BRX was originally set up for 105-107gr bullets.

Truth: Bob said he set up his original reamer with a zero freebore and he has his gunsmith use a throater to throat whatever chamber was being made to where he wanted a particular bullet to touch the lands. Bob said he originally started with a 1:10″ twist barrel and shot a bunch of the 95gr VLDs and also 87gr bullets. Later he used an 8.5″ twist barrel for the heavier bullets.

Myth Four: The original BRX was set up also for use with Remington BR Brass.

Truth: Bob said he always used Lapua brass. He originally was an avid reader of Precision Shooting magazine and saw that the .262″ neck-turn neck was working real well with the 6 PPC and 6mm BR bench rest shooters and he decided to try to go with something that was already working well for 6mm shooters. He says his original reamer had a .262″ neck, but he also has a .272″ “no-neck-turn” version that he used on some of his rifles. He said the Lapua brass was so good and consistent, that for some rifles he just “didn’t want to mess with it” so he went with the “no-neck-turn” .272″ neck too.

Bob Crone 6mm BRXMyth Five: The “false shoulder” method was used to make brass.

Truth: Bob said he never used the “false shoulder” method to make 6mm BRX brass, he just loaded 6mm BR brass with a bullet well into the lands of the BRX chamber and fire-formed brass that way. He noted that the accuracy with some of the fire-forming rounds was “outrageous” (i.e. outrageously good that is), so much so, they were shot in matches sometimes.

Myth Six: The 6mm BRX has a blown-out or straightened out body.

Truth: Bob said he kept the basic body taper of the 6mm BR cartridge. He wanted the cartridge to be an easy and inexpensive (but high performance) 6mm wildcat, and the original design was (and still is) set up to use readily available 6mm BR dies (up off the shell holder about .100″ from the normal position).

Author’s note: It was a most enjoyable experience to talk to Bob Crone. He is not only still passionate about his 6mm BRX, but he has a commanding knowledge of it as well.

6mm BRX reamer print, Whitley

Reamer Print provided by AR-X Enterprises LLC, www.6mmAR.com.

Permalink Bullets, Brass, Ammo, Reloading 7 Comments »
May 29th, 2011

Satern Custom and Liberty Barrels Halt Grendel Barrel Production

Starting June 1, 2011, Satern Custom Machining and Liberty Barrels will no longer produce 6.5 Grendel and .50 Beowolf barrels, as both barrel makers declined to agree to a new, more onerous licensing agreement with Alexander Arms. Satern had produced cut-rifled 6.5 Grendel and Beowolf barrels for the past five (5) years under license to Alexander, while Liberty crafted button-rifled Grendel and Beowolf barrels under license. It may be hard to replace Satern, a highly regarded cut-rifled barrel-maker, as other top-quality barrel makers may likewise reject Alexander Arms’ licensing demands.

Satern Machining Grendel Barrel

Alexander Arms’ Policies Have Impeded 6.5 Grendel Development
Radford, VA-based Alexander Arms continues to paint itself in a corner with respect to the 6.5 Grendel cartridge. Alexander Arms (AA) has aggressively protected the 6.5 Grendel cartridge design, threatening legal action against companies that planned to sell 6.5 Grendel AR uppers, chamber barrels for this cartridge, or even merely offer 6.5 Grendel reamers. One can understand Alexander’s desire to protect its design rights, but many industry experts believe Alexander Arms has gone overboard. Many gun builders and parts markers view the 6.5 Grendel cartridge as a “lawsuit in the making” so they stay away from it. As a result, this accurate and efficient cartridge is not growing in popularity as rapidly as it might otherwise. Alexander Arms has simply made it too difficult to comply with its demands, so many gun makers have decided that they would rather build anything other than a 6.5 Grendel.

Ironically, many shooters have chosen to build guns based on 6.5 Grendel parent brass, but necked down to 6mm. Robert Whitley pioneered a very effective 6mm-6.5 Grendel wildcat he calls the 6mmAR. It shoots great in AR platform rifles, as does a higher-capacity derivative, the 6mmAR “Turbo”. To learn more, visit 6mmAR.com.

Permalink Gunsmithing, News 11 Comments »
November 13th, 2009

Grendel-based 6mmAR Cartridge for High Power

A full-time lawyer, Robert Whitley is also an avid prone, Highpower, and cross-course shooter. Over the past two years, Robert has pioneered a cartridge for these disciplines (as well as long-range varminting) based on the 6.5mm Grendel necked down to 6mm. Robert calls the cartridge the “6mmAR”.

The 6mmAR cartridge has performed very well in AR-based comp guns, both with shorter bullets loaded to mag length, and 105-107gr bullets single-loaded. Robert has complete info about the 6mmAR on his website, 6mmAR.com, including recommended loads and field test results. Robert has also developed a higher capacity version, with the shoulder blown forward and a shorter neck. He calls this the 6mmAR Turbo. This round can drive 105-108gr bullets in the 2850-2900 range, and it has proven very accurate. It is one of the best options for AR-platform space-gun shooters.

6mmAR brass 6mmAR turbo

Though making 6mmAR brass from 6.5 Grendel brass is quite straight-forward and simple, Robert receives many questions about forming the brass, so he recently prepared a video. The two-minute video shows how quick and easy the brass-forming process can be:

YouTube Preview Image

Robert also builds and sells products for across-the-course shooters, including complete AR uppers, chambered in a variety of calibers, including 6mmAR. Jerry Tierney, 2005 NBRSA 1000-yard champion, has a 6mmAR upper built by Robert and Jerry says the upper “Absolutely shoots great. I love it.” In the past few months, Jerry has broken many NRA senior records with his new 6mmAR-chambered rifle.

CLICK HERE for Feature Article on 6mmAR and Robert Whitley (many photos)

CLICK HERE for 6mmAR LOAD DATA

Permalink - Videos, Bullets, Brass, Ammo, Competition 2 Comments »