Who hasn’t dreamed of having a professional-quality permanent shooting bench on their own property? Well here’s an article that can help you make that dream come true. The latest online edition of RifleShooter Magazine shows how to build a quality concrete shooting bench step-by-step.
All aspects of the construction process are illustrated and explained. The author, Keith Wood explains: “Construction happened in three phases — first creating the slab foundation, then the support pillars (legs), and finally the table.”
Click image below to load article with slide show.
Each step in the process is illustrated with a large photo and descriptive paragraph. Starting with framing the foundation (Step 1), the article illustrates and explains the 15 Steps that produce the finished, all-concrete bench, shown below.
“All dressed up and nowhere to go” was the comment our IT guy, Jay Christopherson, sent with this photo. This is Jay’s testing set-up at his home range, complete with PVM-21 chronograph and wireless target-cam. The camera signal is sent, via WiFi, to Jay’s laptop computer. However, even with all that high-tech electronic gear, you can’t make the shot if you can’t see the target through the rifle-scope. On this morning, heavy ground fog completely obscured the target. Jay told us: “I ended up waiting a little over an hour for the fog to burn off enough so that I could see the 600-yard target. What was funny was that I had a perfectly clear picture of the target via the target-cam and monitor. But there was no way to aim the rifle since the riflescope showed nothing but fog.”
This photo was taken by Jay at the Cascade Shooting Facility in Ravensdale, WA. The rifle is Jay’s .284 Shehane F-Class rifle. Jay was testing primers for Extreme Spread (ES) variation around 9:00 am. Nature was not cooperating. Jay was running Hodgdon H4831sc and testing various primers to see which provided the best numbers.
The chronograph is the Kurzzheit PVM-21. Equipped with infrared sensors, the PVM-21 is our “go-to” chron for most velocity testing, with an Oehler 35P for “back-up”. The PVM-21 (now updated with Kurzzheit’s BMC-19 model) sets up quickly and gives reliable results in any light conditions. But there is something even more sophisticated on the horizon — the new Labradar, a “stand-off” chronograph that uses Doppler radar to measure bullet speed.
Jay explains: “I am (somewhat) patiently waiting for the new Labradar to release. The PVM-21 works pretty well most of the time and is easy to setup. I do get odd readings out of it every so often, but they are pretty obvious when they occur.” The advantage of the Labradar (if it ever comes to market) is that the unit sits to the left or right of the rifle. The Labradar is situated out of the bullet path, so there is no chance of shooting the chronograph by accident. Another advantage of the Labradar is that you can set it up without needing to go forward of the firing line, which would require a safety break.
If you’re one of those folks who doesn’t wear eye protection, you need to check out the LuckyGunner Labs Eye Protection Test. For those who DO wear safety glasses — don’t assume that everything is OK. Just because you purchased name-brand “safety glasses” doesn’t mean that you are getting truly effective protection. In fact, many forms of protective eyewear sold today are flimsy, or poorly made. Consequently, they won’t stop even low-energy, slow-velocity fragments.
Two years ago, LuckyGunner Labs conducted very extensive field tests of 28 types of eyewear, ranging in price from $7 to $220. Remarkably, some of the most expensive safety eyewear performed no better than $10 items. Many of the products failed shockingly — with the lenses coming right out of the frames when hit with pellets. LuckyGunner recorded these kind of failures even with ANSI Z87-“approved” eyewear. The reason is that the Z87 test is not tough enough: “The basic ANSI standard is referred to as Z87, and you’ll see this marked in a number of locations on most eye protection marketed to shooters. However, the Z87 impact standard involves a .25″ steel ball traveling at 150 fps — this is fine for protecting eyes from debris that might fall or be thrown, but is not extremely relevant to shooters, who are dealing with objects traveling at much higher velocities.”
Standard
Impact speed
Caliber/Size
ANSI Z87.1-2003
High Velocity
150 feet/second
45 meters/second
0.25″ diameter steel ball
(25 caliber)
Mil-PRF-31013
Vo ballistic test
640-660 feet/second
195 meters/second
0.15 inch diameter steel projectile (15 caliber)
The testers recommend you select eyewear that meets military specification (above and beyond ANSI Z87). The MIL-PRF-31013 Standard covers projectiles up to 650 feet per second. This is much more stringent. Additionally, you want to replace often-used protective eyewear every year or so. Long-term exposure to UV radiation can weaken polycarbonate and lessen its ability to withstand impacts.
SUMMARY — What to Look for in Protective Eyewear
THE GOOD — Eyewear Protects Against Direct Hit with .22 Short Bullet
APEL Revision Sawfly eyewear was shot with a .22 Short, pushing a 29 grain bullet at 710 fps. That’s not powerful by modern firearm standards, but this might be fairly representative of a ricochet bullet fragment. The Sawfly lens stopped this 29gr bullet with minimal damage to the cheek area.
THE BAD — Remington Eyewear Lenses Separate. Right Lens Enters Eye Socket
The most gruesome example was the cheap Remington eyewear which shed both lenses back towards the eyes, one of which embedded itself into the eye socket. The real-world implications of this action are disturbing to say the least.
THE UGLY — Prescription Glasses Failed Miserably
Many ranges don’t see any need for protective eyewear beyond prescription glasses. However, most prescription lenses offer little if any protection. If the prescription lenses are glass, this can create more problems. As shown below, these prescription glasses offered no ballistic protection, and, in fact, proved more dangerous to the eyes due to the flying glass shards.
Results Chart, Video Clips, and Photos copyrightLuckygunner.com.
Summary and Conclusions:
For faster-moving projectiles such as ricochet fragments, you need high quality, tested eye protection. LuckyGunner recommends eyewear with a single (one-piece) lens for any activity where your face might be struck by small, fast-moving objects. Individual lenses detach from the frames once a certain level of force is reached, and they are driven back into the eye sockets, where considerable damage may be done. There are good examples of protective eyewear with two separate lenses, but a broad, one-piece lens distributes force much better.
A wide, comfortable, and preferably soft rubber nosepiece is critical. Along with good “arms”, this will serve to keep the eye protection in place and will also reduce the chances of the lens being driven down or back into the face with enough force to damage the orbital bones.
A frame that connects across the top of the lens, not individual arms which attach to the outside corners of the lens, is recommended. This will reduce the chances of the lens detaching from the frame under impact (it’s still possible, just less likely). Some types of eye protection actually use the frame to absorb impact and distribute force.
NOTE: Andrew, the author of the LuckyGunner Eyewear report, was a former Navy Corpsman. Accordingly, he is familiar with health and safety matters.
One of our Forum Members has a .308 Win load that dips into the transonic speed range at 1000 yards. He is concerned that his bullets may lose accuracy as they slow to transonic speeds: “My target is at 1000 yards. How important to accuracy is it to keep the bullet supersonic (Mach 1.2) all the way to the target? How does slowing to transonic speeds in the last 100 yards or so affect accuracy?”
TargetShooter Magazine and AccurateShooter.com contributor Laurie Holland offers some practical answers to this important question, based on his his experience with .223 and .308-caliber bullets.
Thoughts on Accuracy and Transonic Bullet Speeds by Laurie Davidson.
There is no simple answer to the question “How do transonic speeds affect accuracy”. Some bullets manage OK, some not so well, some fail entirely, and I’ve never seen a guide as to which models do and which don’t. But we do have the ‘boat-tail angle rule’, anyway. Bryan Litz says the ideal boat-tail angle is 7-9°. Go much above 10° and it’s too steep for the air to follow the bullet sides around to the base. This seems to manifest itself as much increased drag and turbulence leading to instability in transonic flight.
It is this effect that has led to the common advice of “Don’t use 168gr 30-caliber bullets at 1000 yards”. That is misleading advice as it resulted from use of the 168gr Sierra ‘International’ (aka MatchKing) bullet with its 13-deg BT angle. (This was, originally, a specialized 300m design — there are various near copies on the market from Speer, Hornady and Nosler.) By contrast, Berger 168-grainers are designed as long-range bullets with 8.9, 8.5 and a really nice 7° angle on the BT, VLD and Hybrid respectively. Hornady A-Max 30-cal projectiles (other than the 208-grainer) fall into this enforced shorter-range bracket too thanks to their 12.6° (and greater) boat-tail angles. (155gr = 13.5°, 168gr = 12.87°, and 178gr = 12.6°.)
Even this boat-tail angle ‘rule’ doesn’t always seem to apply. Many older long-range Service Rifle shooters talk about good results at 1000 yards with some batches of 7.62mm match ammo in their 20″-barreled M14s using the 168gn SMK. I’ve successfully used Hornady and Sierra 168s at 1000 yards in 30-cal magnums which drive the bullets fast enough to keep out of trouble at this distance. This is still not recommended of course thanks to their low BCs compared to better long-range speciality bullets.
These four photos show the substantial changes in the shock ware and turbulence patterns for the same bullet at different velocities. The “M” stands for Mach and the numerical value represents the velocity of the bullet relative to the speed of sound at the time of the shot. Photos by Beat Kneubuehl.
Transonic Issues with .223 Rem in F-TR
I was much exercised by [concerns about transonic instability] in the early days of F-Class, when I was shooting a .223 Rem with 80-grainers at 2,800 fps MV or even a bit less. Even the optimistic G1 ballistic charts of the time said they’d be subsonic at 1000 yards. (Bryan Litz’s Point Mass Ballistic Solver 2.0’s program says 1,078 fps at 1000 yards at 2,800 fps MV in standard conditions for the SMK; below 1.2 MACH beyond a point somewhere around 780 yards.) In fact they shot fine in a large range of conditions apart from needing around 60% more windage allowance than 6.5mm projectiles [shot with a larger cartridge]. The biggest problem apart from my wind-reading skills was constantly getting out of the rhythm to call to have the target pulled as the pits crew didn’t hear the subsonic bullets and had trouble seeing their little holes.
In the early days of F-TR I used a 24″ barrel factory tactical rifle that was billed as F-TR ready — it wasn’t! The much touted 175gr Sierra MatchKing, as used in the US military M118LR sniper round, was allegedly good at 1000 yards at .308 velocities — but it wasn’t! It would group OK in [some calm] conditions, but any significant change would cause a much greater deflection on the target than the ballistic charts predicted, so transonic flight was obviously making it barely stable. I also suspect conditions on the day had a big effect as Litz’s program says [the 175gr SMK] is just subsonic at 2,650 fps MV at 1,000 in standard conditions. Throw in MV spread and there was a risk of some round remaining supersonic, while others went transonic. Plus warmer or colder air moving onto the range under some conditions might change things.
I used the combination on Scotland’s notorious Blair Atholl range at 1000 yards in one competition in a day of cold headwinds from the north and frequent rain squalls. The temperatures plummeted during the squalls (and the wind went mad too!) and what was an ‘interesting group pattern’ outside of squall conditions changed to seeing me do well to just stay on the target frame at all. On ranges other than Blair (which is electronic, so no pits crew), target markers reported they heard faint supersonic ‘crack’ and saw round holes on the paper, so the bullets appeared to remain stable and just supersonic in summer shooting conditions.
Transonic Problems with M118LR 7.62×51 Ammo
Confirmation of this transonic performance phenomenon has since come from USMC snipers who say the M118LR’s performance ‘falls off a cliff’ beyond 800m (875 yards), which is just what I found when shooting the bullet at slightly higher than M118LR muzzle velocities. A move to the 190gr SMK with Vihtavuori N550 keeping the MVs reasonable gave a vast improvement in 1000-yard performance.
Practical Advice — Use a Bullet That Stays Supersonic
The ‘easy’ / better answer to all this is to use a design such as the 30-caliber, 185gr Berger LRBT with a reputation for good long range performance and to load it to achieve or exceed 1,350 fps at 1000 yards. If I can get the combination I’m using to be predicted to hold 1,400 fps at this range in a G7-based program calculation, I’m happier still.
Incidentally, the old long-range, 30-cal Sierra bullets (the venerable 190gr, 200gr, and 220gr MatchKings), with their extra length boat-tail sections, have a superb reputation for stable transonic / subsonic flight. They were used by GB and British Commonwealth ‘Match Rifle’ shooters at 1000, 1100, and 1200 yards for many years before the current bunch of 210gr and up VLDs and Hybrids appeared.
Transonic vs. Supersonic
The term “Transonic” refers to velocities in the range of Mach 0.8 to 1.0, i.e. 600–768 mph. It is formally defined as the range of speeds between the critical Mach number, when some parts of the airflow are supersonic, and a higher speed, typically near Mach 1.2, when the vast majority of the airflow is supersonic. Instability can occur at transonic speeds. Shock waves move through the air at the speed of sound. When an aircraft goes transonic and approaches the speed of sound, these shock waves build up in front of it to form a single, very large shock wave. This is dramatically illustrated in this Space Shuttle photo.
Brass jags perform well for their intended purpose — with one hitch. Strong copper solvents can actually leech metal from the jag itself, leaving the tell-tale blue tint on your patches. This “false positive” can be frustrating, and may lead shooters to over-clean their barrels.
Gunslick Nylon Spire-Point Jags
There are now some good alternatives to brass jags. The best may be the Gunslick® Nylon Snap-Lock™ jags shown at right. These never leave a “false positive”. A while back, Larry Bartholome, past USA F-Class Team Captain told us: “The best spear-type jags I have used are the GunSlick black nylon tips. I have used the model 92400 for the last couple years in my 6BR and 6.5-284s. Unlike the white plastic jags, these are strong and there’s no brass to worry about.” You can purchase these nylon jags directly from GunSlick just $1.49 each. At that price, they’re worth a try.
#92400 for 22 through 270 calibers: $1.49
#92421 for 30 through 375/8mm calibers: $1.49
#92423 for 38 through 38/9mm calibers: $1.49
Tipton Nickel-Coated Jags
If you prefer a metal jag, consider the Tipton Nickel-coated Ultra Jags, sold both individually and as a boxed set. All Tipton nickel-plated jags have 8-32 thread, except for the .17 caliber jag which has a 5-40 thread. The vast majority of user reviews have been very positive. A few guys have complained that the nickel-plated Tipton jags run oversize, but we use a .22-caliber jag in our 6mms anyway, so this hasn’t been a problem for us. Both the .22 cal and the .243/6mm cal nickel-plated jags cost $3.08 each at Midsouth. The complete 12-jag set, covering .17 to .45 calibers, including a flip-top carry case, is offered by Midsouth Shooters Supply for $17.62 (Midsouth item 094-500012).
Tipton also makes a nickle-plated 12-Jag Kit in a flat version with a see-through top. Sold by MidwayUSA for $16.99, this features an easy-to-use, clear-topped fitted caddy that can lie flat on your bench, or be attached vertically (to save space).
Clear-Coating Your Brass Jags
If you’re reluctant to give up your collection of brass jags (after all they’ve worked pretty well so far), try covering the jag itself with a thin, transparent coating. Forum Member BillPA says: “I give the brass jags a coat of clear lacquer or acrylic; that works for me”. You may need to experiment to find a coating that stands up to your favorite solvent. BillPA says: “The only solvent I’ve found that eats the lacquer off is TM Solution. Butch’s, Shooter’s Choice, or Wipe-Out don’t seem to bother it. Most of the time I use rattle-can clear lacquer”. If you’re feeling creative, you could even color-code your jags by adding tints to the clear-coat.
October’s just around the corner — that means temperatures will be dropping soon in Northern climes. In a month or two, many of you will be putting your guns into storage for many months. To prevent rust from forming on your valuable firearms, you’ll want to control the temperature and humidity in your safe. By maintaining a warm temperature you can keep the relative humidity (in your safe) above the dew point and prevent moisture from condensing on your guns. One popular way to keep a safe warm is to use a Goldenrod. Though marketed as a “de-humidifier”, the Goldenrod tube is actually a simple electric heater. Placed in the bottom of your safe, the Goldenrod can help keep the relative humidity above the dew point.
Rope Lights — Light and Heat for Your Gun Safe
While Goldenrods work, they only provide heat, and Goldenrods typically retail for $20.00-$30.00. There is a less expensive solution that provides both light AND heat. A section of incandescent Rope Lighting will light up your safe AND warm the air. A 6-foot section of rope lighting costs about $6.00 at Lowes. The 6-foot strands can be linked together in longer chains. Rope Lighting can easily be installed in your safe with clips or velcro fasteners. One 6-foot long incandescent Rope Light draws about 18 watts of power — the same as an 18″ Goldenrod. Sheathed in plastic tubing, the incandescent Rope Lighting is slightly warm to the touch. A single 6-foot long strand of incandescent Rope Lighting maintains this Editor’s 23-cubic-foot indoor safe comfortably above 65° F all the time. (If you live in a colder area, or keep your safe in the garage, you may need a longer Rope Light, or a Rope Light in combination with a Goldenrod. Incandescent Rope Lights draw about 0.25 watts per bulb or about 3 watts per foot. Goldenrods draw about 12 watts per foot of length.)
Not All Rope Lighting is the Same — Incandescent vs. LED
Thus far, we’ve been talking about incandescent Rope Lights. For more money, you can also purchase energy-efficient LED ropes. LED Rope Lights draw much less electricity, but they won’t provide as much heat as incandescent Rope Lighting. It you use LED strands, you need to string longer sections to warm your safe. Or, just use LED strings for interior lighting only and then add a Goldenrod for heat.
Monitor Temp and Humidity with Thermometer/Hygrometer
To ensure that your safe’s interior is staying warm and dry, you can place a small temp/humidity sensor inside the safe. You can use either an Analog (dial-type) Thermometer-Hygrometer, or a battery-powered Thermometer-Hygrometer with digital read-out. Both digital and analog units can be purchased for $10 to $15 from internet vendors. Some of the digital units have dual temp sensors, so you can monitor the temperature both inside and outside your safe. That lets you gauge how well your safe-warming system is working.
WARNING: As with all electrical products, use caution with rope lighting. Follow manufacturer’s instructions. Avoid placing ropes in direct contact with paper or other flammable objects. Monitor surface temperatures.
For years, many shooters have coated bullets with Moly (molybdenum disulfide) or Danzac (tungsten disulfide or “WS2″). The idea was to reduce friction between bullets and barrel. In theory, this could lengthen barrel life and extend the number of rounds a shooter can fire between cleanings.
Moly and WS2 both have their fans, but in the last couple of years, some guys have switched to Hexagonal Boron Nitride (HBN), another dry lubricant. The advantage of HBN is that it won’t combine with moisture to create harmful acids. HBN is very slippery and it goes on clear, so it doesn’t leave a dirty mess on your hands or loading bench. Typically, HBN is applied via impact plating (tumbling), just as with Moly.
HBN Results — Both on Bullets and Barrel Bores
Many folks have asked, “Does Hexagonal Boron Nitride really work?” You’ll find answers to that and many other questions on gunsmith Stan Ware’s popular Bench-Talk.com Blog. There Paul Becigneul (aka Pbike) gives a detailed run-down on HBN use, comparing it to other friction-reducers. Paul also discusses the use of HBN in suspension to pre-coat the inside of barrels. Paul observes:
We coated our bullets … how we had been coating with WS2. Now our bullets have a slightly white sheen to them with kind of like a pearl coat. They are so slippery it takes a little practice to pick them up and not drop them on the trailer floor. What have we noticed down range? Nothing different from WS2 other than the black ring on your target around the bullet hole is now white or nonexistent. Our barrels clean just as clean as with WS2. Your hands aren’t black at the end of the day of shooting and that might be the most important part.
Interestingly, Becigneul decided to try a solution of HBN in alcohol, to pre-coat the inside of barrels. Paul had previously used a compound called Penephite to coat the inside of his barrels after cleaning. Paul explains:
If Penephite was used because it was slippery wouldn’t HBN be better? … We called Momentive again (our source for HBN), and talked about mixing HBN and 90% alcohol for a suspension agent to pre-lube our barrels. He though it sounded great but that the Kb>AC6111 Grade HBN would be better for this use. It would stand up in the alcohol suspension and cling to the barrel when passed through on a patch. We got some and mixed it in alcohol 90%. We use about one teaspoon in 16 ounces of alcohol.
We started using it this fall and what we have noticed is that now that first shot fired out of a clean and pre-lubed barrel can be trusted as the true impact point. We use tuners so now I got to the line, fire two shots judge my group for vertical, adjust the tuner as needed or not, and after tune has been achieved go to my record targets. This use has saved us in time at the bench and bullets in the backstop.
You really should read the whole article by Becigneul. He discusses the use of barrel lubes such as Penephite and “Lock-Ease” in some detail. Paul also provides links to HBN vendors and to the Material Safety Data Sheets (MSDS) for the various compounds he tested.
Good Source for Hexagonal Boron Nitride (HBN)
Paul Becigneul (aka PBike in our Forum) has been using HBN for many years with good results. He obtains his HBN from Momentive Performance Materials:
The National Shooting Sports Foundation (NSSF) has created a video with helpful tips on mounting scopes, and adjusting the position of scopes to suit the shooter. This video, hosted by Ryan Cleckner, a former U.S. Army Sniper instructor, is aimed primarily at “hard-holders” who shoot prone. The video should prove useful for tactical shooters, varmint hunters, and F-Class shooters. Ryan does explain that, if you plan to use your rifle in standing, sitting, and prone positions, you need to set the scope in a “happy medium” position that provides sufficient eye relief in all shooting positions.
Ryan has an interesting method for leveling a rail-mounted, flat-bottomed scope (i.e. one with a flat surface under the turret housing). He simply inserts a small metal bar between rail and scope, and aligns the straight edges along the bottom of the scope turret housing with the flats on the rail (see photo). Watch how he does this on the video — it’s pretty clever. One other highlight of the video is the segment where Ryan shows how to adjust the ocular on his Leupold scope to provide the best (sharpest) image of the reticle. Ocular/reticle adjustment is covered in minutes 11:00-13:00 of the video.
The video has some faults. Some of the advice, such as “always mount the scope as low as possible” is counter-productive for benchrest shooters who want to keep their heads OFF the stock. In addition, Ryan does not explain that, with a variable power scope, proper eye relief may change considerably with the level of magnification. If you have an 8-32X scope, for example, you can set everything up perfectly for 8X magnification, only to find that you need a LOT more eye relief at 32X. We recommend positioning the scope so it provides sufficient eye relief at the highest magnification you regularly use.
While many folks enjoy the convenience of an electronic powder scale/dispenser such as the RCBS Chargemaster, some hand-loaders still prefer to use a traditional balance beam. Balance beam scales are simple, compact, and don’t suffer from electronic “glitches”. Morever, even if you use a digital dispenser at home, when you’re doing load development at the range, a balance-beam scale may be more convenient. A scale doesn’t require electrical power, so you don’t need to bring battery packs or string long power cables. Just bring some kind of box to shelter your beam scale from the wind.
While designs like the RCBS 10-10 are decent performers as built, they can be made much more precise (and repeatable), by “tuning” of key parts. Forum member Scott Parker optimizes a variety of popular beam scales, including the Ohaus 10-10 (USA-made model), RCBS 10-10 (USA-made model), RCBS 5-10, Lyman M5, Lyman D5, and others. You send Scott your scale, he tunes the key components, tests for precision and repeatability, and ships it back to you. The price is very affordable ($65.00 including shipping in USA).
Scott tells us: “I have tuned several 10-10s. They all have turned out very sensitive, consistent and hold linearity like a dream. If only they came that way from the factory. The sensitivity after tuning is such that one kernel of powder registers a poise beam deflection. For repeatability, I remove the pan and replace it for the zero 10 times. The zero line and the poise beam balance line must coincide for each of those 10 tries. I then set the poises to read 250.0 grains. I remove and replace the pan 10 times with the calibration weight. For linearity, the poise beam balance line and the zero line should coincide within the line width. This is roughly one half a kernel of powder. For repeatability, the poise beam balance line must return to that same balance point ten times. I then adjust the poises back to zero and recheck the zero. I have a master’s degree in chemistry, thus I am very familiar with laboratory balances. Email me at vld223 [at] yahoo.com or give me a call at (661) 364-1199.”
The video above, created by British shooter Mark (aka 1967spud), shows a 10-10 beam scale that has been “tuned” by Scott Parker. In the video, you can see that the 10-10 scale is now sensitive to one (1) kernel of powder. Mark also demonstrates the’s scale’s repeatability by lifting and replacing a pan multiple times. You can contact Mark via his website, www.1967spud.com. To enquire about balance-beam scale tuning, call Scott Parker at (661) 364-1199, or send email to: vld223 [at] Yahoo.com.
Video tip from Boyd Allen. We welcome reader submissions.
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!
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).
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.
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.
Transonic vs. Supersonic
Gunslick Nylon Spire-Point Jags
Tipton Nickel-Coated Jags
Momentive Performance Materials
The 
