AR-15 Fliers, Part 3

Let’s move on from basic AR design flaws and ammunition into other contributors to fliers. The first of these are iron sights that fail to track, have lags in tracking, or dead spots. I have been shooting Stoner firearms ever since the 1960s Viet Nam era. The early versions started out with fairly coarse sight adjustments. As time went on adjustments became finer by substituting parts with finer threads, with current iron sights down to 1/4 minute clicks these days.

It seems to me that finer threads of modern sights wear out much sooner than coarser threads. I believe the finer threads are also more susceptible to debris causing temporary and permanent issues. Ray-Vin makes a stellar iron sight checker but it must clamp onto a carry handle so it may not work with some of the backup sights on the market today. Wear out of rear sight parts was so common that in my decade as match Armorer for the Army Reserve Shooting Team it was my number one repair chore.

Issues with scopes is next. If you suspect a problematic scope, begin checking the mount and rings for tightness. Parallax is another issue. A scope that is parallax free (or nearly so) at one distance can exhibit lots of parallax at some other distance. I ask the shooter early on if he is having more fliers at a given distance. This obviously assumes using the same ammo at all distances.

In some shooting disciplines it is common to shoot magazine-length ammo at shorter distances and then switch to long seated ammo at longer ranges. If the shooter’s problems coincide with an ammo switch that points to the need to check both parallax and ammo at the distance the shooter is having problems with. Scopes lacking parallax adjustments should have a parallax-free distance in the owner’s manual.

If the bread crumbs are leading to a parallax issue, the scope will need to be field tested at all distances with emphasis on the range where the shooter is having greatest problems. After ensuring that the firearm is clear and on safe, I set the upper in a solid support, find a distinct aim point down range, and naturally settle the crosshairs on it. Then, without touching the upper or sight, I move my head right to left and up and down while watching the center of my crosshairs.

Apparent movement of the crosshairs in relation to the target indicates parallax at that distance. If the shooter observes parallax at distances that the factory literature says shouldn’t be, there isn’t much that a gunsmith can do and it is best to contact the manufacturer.

On the other hand, if the shooter is experiencing parallax at other distances, the easiest fix is better application of shooting fundamentals, specifically, being keeping the head and eye in the exact place and aiming perfectly straight through the scope. A more consist stock weld may be all that’s needed. I find the original AR stock just fine if the optic is mounted on a flat top.

Scopes mounted on a carry handle offer a challenge in getting a proper stock weld because the head is too high and the cheek weld likely compromised. Of course, it helps if you spent the last half century with your cheek "welded" to AR stocks. If you do not find this natural, aftermarket stocks with adjustable or raised cheek pieces can be had. Check your rulebook to ensure they’re allowed. How does the shooter know prior to firing a bad shot that his eye is not lined up with the center of a scope?

A dark shadow anywhere on the outside edge of the field of view is a reliable clue. Shots fired with a quarter moon shadow will often lead to a flier. Always check there is no shadow prior to firing. There are scope covers (Accu Cover and Ray- Vin make examples) that assist with keeping centered. While we are on the general topic of stocks, good marksmanship dictates keeping the butt in the same position in the shoulder for each shot.

Gunsmiths need to check that the buffer tube is tightly screwed into the receiver and that the top screw on the butt is tight. Try to wiggle or rotate the stock; a lack of movement indicates the stock mounted right. Cheaper adjustable stocks have too much play in them, given the same effect as mounting the stock differently every shot. Shim stock may help, but I recommend getting a quality adjustable stock. The Magpul UBR is a good option.

Top end scopes often have adjustable parallax to dial in the target distance. If you are testing such a scope and note a little parallax, move the adjustment knob both a little more or less of the manufacturer’s recommended setting as they might not be perfectly spot on. Lags and dead spots also happen with optics. Diagnosing requires shooting groups while noting how well the click adjustments track. Dead spots or lags require the optic to be returned.

One technique that seems to lessen adjustment issues is to go past, then return to the desired setting. Say three clicks of adjustment are needed, I’ll put on six, and then return back three. Finally, I can not over emphasize the importance of buying the highest quality optic you can afford. Yes, this may require taking out a second mortgage on your home. And, yes, you can easily spend as much on a quality scope as you spent on the upper or entire rifle itself.

Magazines Grab any AR in your gun safe that has a regular carrier in it. Clear it, place it on safe, let the bolt go forward on an empty chamber leaving the ejection port cover open, and point the muzzle in a safe direction. Take any 20 or 30 round magazine that you may have and charge it with a few dummy rounds. Carefully watch the front section of the bolt carrier that is visible through the ejection port as you slowly push the magazine up.

Just as, or a little before, the magazine locks into place you will see the bolt carrier move up. There are dimensional differences between magazines so it is entirely possible that one magazine may give more or less lift than the next. Your eye is likely not precise enough to see these differences in lift but your gun will notice these differences which can move the impacts of rounds fired from various magazines. Far When locked in place it is very rigid. I didn’t invent this.

I was aware from decades past that National Match pistol shooters used machine rests to check magazines for any shifts in point of impact. Military shooting teams were doing the same thing with M14s. However, when I was a firing member of the Army Reserve Shooting Team during the M14 era we didn’t have a machine rest and were in the dark about this. When I became the Armorer I had my own rifle machine rest for a variety of tests, including magazines. The results were eye opening, shown in the target scans here.

My December 2015 article highlighted this important topic. Bore Issues I’m certain you’re aware of the importance of bore cleaning. After every range session, clean the bore, including using a chamber brush, and the bolt carrier assembly. For storage longer than a few days, use an anticorrosion product on the bore, such as Boe Shield or WD-40. My January 2015 article goes into detail. Barrel lands are paper-thin and easily damaged during cleaning.

Stainless steel is in particular risk as it’s softer than chrome-moly steel. 5R lands are also easily damaged. Bore guides are supposed to help but some of them are not perfect. My June 2018 article describes a two-piece cleaning rod guide from PMA Tool that is a recommended improvement. Almost all rifles will shoot one or two fliers (fouling shots) right after cleaning. This should be expected, although the severity will vary between firearms. Unfortunately, I don’t know

how to prevent this. If any of the 14 people who normally read my articles have discovered some elixir or method to eliminate first round fliers, please contact me and I’ll contribute the fix to help all readers. Uneven land start points. Most gunsmiths trying to diagnose fliers will eventually grab a bore scope. I begin my observations by looking for fouling. This is especially important in instances where the gun owner says his gun just mysteriously started shooting fliers.

It is also important when customers say they are having a sudden problem with pressure. Either issue can be caused by a buildup of fouling just in front of the chamber. In both examples I almost always admonish shooters to take the gun home and, "J-B the heck out of the back of the barrel".

J-B Bore Cleaning Compound won’t harm the lands by itself, however, since the owner is reversing the direction of travel of the patch inside the bore, it is super important to use a highquality bore guide like the two-piece PMA guide. The second priority for my borescoping observations is the start point for the lands just in front of the chamber. These need to be even, which they are when the barrel is chambered.

The hot gasses formed when cartridges are fired will erode the land start points forward as the gun ages, but those start points will remain even. The only thing I have found that will cause one or two land start points to appear forward of their siblings is damage to them caused by cleaning rod flex. Rod flex in small caliber firearms is a big deal!

There is so much flex in the cleaning rod I use to clean my Anschutz squirrel rifle chambered in 17 Hornady Magnum Rimfire that I can’t even push a bore patch through the barrel. Instead, I have to carefully insert my cleaning rod in the bore, attach a patch, then pull it carefully through the bore. Cleaning rods of .22 caliber are little better. The lands only stick up above the grooves by about the thickness of a sheet of paper and it is super easy for rods flexing into them to wear those lands down.

Stainless steel is softer than chrome-moly and more susceptible to damage. Uneven starting lands normally indicate the barrel is toast! Fat groups and fliers will result and there is no quick fix. Gun owners will often have a hard time accepting this because they will not have felt the rod flex, especially when it occurs at a low round count. As discussed with ammunition issues, one of the first hints that land start points have been damaged is erratic length-to-lands readings. A bore scope can see this.

While you have the bore scope out, I suggest looking for bore pitting. Pitting results from storing guns without cleaning and a rust preventative. A lot of deep pitting in the bore will usually permanently ruin accuracy. Pitting at the muzzle and crown is particularly destructive to group sizes. Mild pitting can sometimes be salvaged by recrowning.

Stainless steel resists corrosion better than chrome moly, the reason stainless was first accepted by the hunting fraternity, but chrome-moly barrels average 9.6% tighter groups sizes. My preferred corrosion protection salt bath nitride processing. Note, a barrel must be properly broken in before nitriding and remove the barrel extension before sending. When the barrel is returned, re-time the extension using 150 foot-pounds of torque as originally applied. My September 2013 article details this further.

All barrels, including stainless and nitrided, need a rust preventative burnished into the bore for storage. Add a good spray in the chamber and muzzle face as well. A quality, preferably two-piece, guide rod is the best damage preventative. For you grownups, they also make one to fit the AR-10. Quality bore guides are like studded tires, air bags, and seat belts in cars: All are good insurance but not a guarantee. Also, clean often, every time you shoot the firearm.

Don’t allow fouling to build up to the point that you have to aggressively scrub it out. Walkers This usually begins with a cold barrel. The first shot lands outside of where the shooter expects, the second a little further, usually in the same direction, and the next even more. Eventually, the gun warms up enough to shoot a kinda/sorta group. All rifles can exhibit this.

Since Stoner rifles connect dissimilar metals in the barrel and upper, I suspect walkers may be more severe, although I confess to have not conducted any scientific studies to verify my suspicion. The observations I have made of this abnormality are that it usually occurs in button-rifled stainless barrels. Quite often I see it in "low bid" barrels that are rapidly cranked out of a few plants. Button rifling puts a lot of stress in a barrel and that must be removed.

If this stress relieving process is rushed, some barrels may

leave the factory displaying a tendency to walk. In fairness to barrel manufacturers, it is possible that many of them are turning out barrels that have been properly stress relieved only to have it reintroduced by someone else. If the outside dimensions of a button-rifled barrel are changed it is possible the inside dimensions are also changed. Any outside machining, such as contouring or fluting, can cause this.

If a gunsmith rushes a cutting or machining process and that produces excess heat, stress could be reintroduced. When I was the USAR Armorer I had success fixing such machining-induced stress problems via cryogenics, as detailed in my September 2016 article. Obviously, the best way to deal with barrel stress is to avoid introducing it in the first place. Some barrel makers offer to perform services like contouring or fluting right at their factory before the barrel leaves.

That way they can perform final lapping, stress relieving, and inspections to ensure quality control. The cut rifling process induces far less stress to a barrel and my studies indicates better accuracy on average. Brux, Satern, Krieger, and Bartlein all perform cut rifling and I have never encountered a chrome-moly cut rifled barrel from any of these plants that turned out to be a walker. Loose flash suppressors or barrels unscrewing from their extensions both create similar symptoms.

I have had this happen twice to personally owned firearms. The first happened to a Colt Python at around the 200,000 round count with impacts tracking left on target. I adjusted the rear sight and resumed shooting only to have the impacts begin tracking left again. Being the slow learner that I am, I repeated this scenario a couple more times until I was near to running out of windage. Finally, I started going over the pistol and discovered that the barrel was unscrewing from the frame.

I removed the barrel and degreased the barrel and receiver threads. After drying, I applied a heavy dose of red Loctite and hand screwed the barrel on to the limit of my strength. After a couple of days of letting the Loctite set up, my next ranges session showed my zero returned to normal.

I still have the revolver and the barrel has remained firmly in place, having since killed a nice Pennsylvania six-point buck and earning my first (Police Combat) of three Distinguished gold marksmanship medals, so I would say that quick repair job all those decades back was time well spent! Later in life while shooting an AR-15 with iron sights I started to observe impacts moving to the left, similar to the incident with my Python.

I must have learned something with the pistol experience because it took me less time to diagnose the problem. The fix was the same and the return to normal zero was similar to the Python. The rifle barrel remained in place until it finally shot out. This brings us to a discussion of torque. Decades back, smart guys discovered that AR flash suppressors installed with too much torque caused large groups and fliers.

I have a military technical manual that recommends 15-20 foot-pounds and had a custom suppressor come in my shop recently that recommended 30-35. Ugg! When I see uppers come in my shop for repairs and they have a crush washer, I just shudder. Crush washers contribute to fliers and I recommend doing away with them. Custom gunsmiths over-reacted to heavy torque and started putting the suppressors on hand tight with red Loctite.

After time, many of those hand-tightened suppressors came loose and fliers were often the result. I use a torque wrench set to three foot-pounds with plenty of red Loctite and haven’t had any units come loose. A flash suppressor that is unscrewing will not necessarily cause bullets to walk in a well-defined direction like a loose barrel; they will cause fliers and loss of zeroes, however. Loose suppressors are usually easy to diagnose by just grabbing the unit and trying to rotate it.

Obviously, this test needs to be conducted after completely clearing the rifle! Around the same time as hand tightening of flash suppressors was briefly in fashion, the same idea got transferred to attachment of barrel extensions. Nearly all of those extensions came loose. Extensions call for 150 foot-pounds of torque. I put mine on to that standard and have never had one come loose. Recoil Reducers Recoil slows recovery time between shots.

Dealing with recoil is critical when firing multiple shots in a tight time limit. Both of the Service Rifle models that I used to compete with had cavities in the buttstock where battlefield soldiers stored segmented sections of cleaning rods and related equipment. Way back in the day competitive shooters learned to place rolls of change in some of these cavities to add weight in an effort to reduce recoil.

I later learned to embed mercury recoil reducers in the stocks of both the M14 and AR- 15 to perform recoil reduction. For decades resourceful companies have made devices that replace the standard AR buffers. Many of these recoil reducers strongly resemble scaleddown versions of automotive shock absorbers. They are usually spring

loaded and act to slow the bolt carrier at the rear most portion of its travel. Without such a replacement buffer the carrier and stock buffer will slam to a stop, jarring the rifle and adding to felt recoil. Either adding weight or one of these tricked out buffers are both invisible so guns equipped with one or both outwardly look stock and pass the muster of most Service Rifle match rules. I have used both approaches and feel that they helped me.

My first experience with the controlled venting of gas to control recoil and muzzle rise was with Mag-naport. They used electrical discharge machining to cut little trapezoidal holes in pistol barrels up on either side of the front sight. The theory was that by directing some of the gas up into the atmosphere the muzzle of the firearm would be pushed down not unlike a jet airplane. These trapezoidal cuts could also be applied to rifles and shotguns.

I performed machine rest tests for group sizes of pistols before and after porting and couldn’t find any degradation in accuracy. Smart hombres started to install match barrels to 1911 pistols that were an inch or so longer than stock to add threaded devices. Eventually, baffles were machined into these compensators and pistol shooters swore that the upward muzzle flip of pistols were lessened.

Ground breaking of this work in pistol preceded such attempts in rifle, but AR shooters soon began to experiment with similar devices, attaching them to the existing threads where a flash suppressor normally screwed on. Since this approach obviously is an external modification, this wasn’t legal in Service Rifle but could be used elsewhere. In years of machine rest testing of these contraptions one thing has really jumped out.

Almost all of them cause fliers and bigger groups than equipping the same gun with a regular A2 flash hider. The lone exception is the Harrell’s Precision AR-15 Tactical Tuner Brake, especially the model with two ports located at three and nine o’clock. Once the device is in place, the shooter must fire test groups, tuning it to a sweet spot. This can be a daunting and time-consuming task. Using a machine rest, it can take me the better part of a day.

Pistol machine rests became affordable decades ago but rifle machine rests have never been affordable and are much less available. That is unfortunate because jobs like this are made so much easier and more precise by the use of a machine rest. Conclusions We have just proven that diagnosing and correcting AR-15 fliers is a matter of protracted discussion.

I can easily see where many of you may find the whole topic to be intimidating, especially general gunsmiths who may only get a couple of ARs in the shop each year. The one thing that all gunsmiths can do is to perform due diligence and make darn certain that we never turn out guns that shoot fliers. Each rifle build begins with the selection of a barrel, detailed in my July-August 2017 articles. Important highlights, chrome-moly barrels out-groups stainless by 9.6%.

Don’t chamber a rifle to jump bullets further than necessary. Don’t over spin bullets; use the minimum twist rate necessary. The taller 0.218" lands out shoot the industry standard 0.219" in every AR I’ve tested. Barrels rifled using the cut rifling method out shoot button rifled. Gain twist barrels with the proper rate of gain shoot the tightest groups and the least number of fliers (detailed in my November- December 2013 and December 2016 articles).

Clean barrels shoot tighter groups with less fliers than those with fouled bores. What is a good starting point when a customer brings a gun to you with complaints of fliers? As previously stated, gas tube misalignment and ammunition concentricity are among my first checks. While examining the customer’s ammo I also look at the rims for tears or deformations as well as the bullet tips. I usually bore scope the rifle in question fairly early on and follow that with actual range testing using the machine rest.

The object is to shoot a group with customer-provided ammo and a second group with a known lot of your ammo. If I notice fouling in the bore when I scope it I fire the gun just the way the customer brought it in. If the group is nasty I thoroughly clean the bore and shoot the group over. Almost always the clean bore group will be tighter and have less fliers. I mark the location of the first and second shots after cleaning so the customer can see how far out these fouling shots go.

I realize those that have to travel to a public range won’t be able to take a half day out of the shop to perform range testing and that is unfortunate. Absent this range step you really don’t know if you have a gun problem or an ammo issue. I usually set up the chronograph when I am machine rest testing. The consistency of velocity tells me something about the care that the customer has used in his loading process.

Rounds that chronograph significantly slower than sibling cartridges will land their bullets lower on target than other rounds at longer distances of 600 yards and beyond. If you haven’t found the cause of the customer’s fliers after the above, I would advise referring to Part 1 of this series and checking for those design shortfalls that have been present since the invention of the rifle. I would also be asking the customer all the questions I suggested throughout this article for a hint.

Those of us who have learned to shoot this rifle had to train for countless hours on hot, dusty ranges to sharpen our marksmanship skills. Diagnosing the causes of fliers is not that much different. The more you practice that skill, the better you will get! Feel free to email me at to discuss this or any of the articles I’ve written. AG