Barel tuners have completely taken over in F-Class and in Rimfire. Tuners are gaining popularity in short, and long-range Benchrest, and are even used in Tactical and long-range hunting rifles.
In this article, I will share my thoughts and experience, on the theory, and design, and in part two I will talk about use, and will show sone target examples. When discussing specs, I will focus on my designs.This is not a review of any other product. Do your research, draw your own conclusions, test then invest.
I was first introduced to tuners around 2007 in Tennessee. At the time, I was shooting NRA small bore. I remember seeing at a match, a Bleiker or Grunig and Elmiger rifle with a big metal piece at the end of the muzzle just before the bloop tube. I asked the guy about it, and he told that the big metal piece was a tuner, which he used to tune his barrel to different lots of ammo.
I was very intrigued, and I had Howard Pitts (Pitts Precision) put a rifle together for me. It was based on Anschutz 54 receiver, Lilja barrel, Eliseo chassis and tuner.
I put over 10,000 rounds through that Lilja, I did some tuner testing, but I didn't have a clear goal on what I was trying to achieve. The barrel shot good no matter what brand match ammo I used.
In 2011, I left the Army Marksmanship Unit, and was stationed in Colorado Springs CO. I got in touch right away with Lone Wigger (former AMU member)and started shooting the weekly matches at the Olympic Training Center.
My rifle was capable of shooting "cleans" on the NRA small bore target, but shot big on the International 50m target. The Olympic Training Center was the perfect place for tuner testing. It is an indoor range, equipped with the most precise/accurate target systems in the world. Up until that point, I thought that tuning consisted of turning the tuner in or out, until half inch groups became quarter inch.
What I found was that rifles with, or without tuners, shot different shape and slightly different size groups every time! After multiple discussions with Lones Wigger (a multiple times Olympic Gold medalist) I decided to shoot 10 shot groups and make bold tuner adjustments in between, instead of chasing the smallest five shot group I could get. I concentrated on the shape of the group and score, the size became secondary. I chose tuner setting that produced round groups with no "fliers" over a setting with slightly smaller irregular shaped groups. My 60 shot average went from low 570s to 580. I even shot few mid 580s. For comparison, scores in the upper 590s (597,598) would win a gold medal at the Olympics in 50m prone. Having a plan, knowing what the goal was, and having the equipment capable of achieving that goal made all the difference, and led to success. I still apply the same principals/ technics when developing loads for my centerfire rifles.
So, how do tuners work?
The most common designs, function by manipulating the vertical movement of a barrel during a shot, by adding weight to the muzzle. Tuners can speed up or slow down the harmonics, therefore changing the bullet release point on the vertical plane of the barrel "whip" which results in a different shot dispersion. Size does matter. Bigger/heavier tuners have much more pronounced effect on target.
I have experimented with small, large, aluminum, brass, iron and steel tuners.
That's my rifle with a tuner made out of brass that weighed almost a pound (15oz)
I even tried a carbon fiber tube filed with sand, with a heavy steel tuner attached at the end.
In theory, since sand is one of the most shock absorbent substances , I thought that barrel "whip" would be brought down to almost nothing, resulting in "one hole" groups with very little tuning. Although I did notice a little improvement over the same barrel without the sand and CF tube, it was nothing ground breaking. I concluded that the vertical barrel movement is actually a good thing, it allows us to fine tune our loads.
Several years ago, with the input form my good friend, teammate and one of the pioneers of using tuners in f-class John Myers, I developed the KMR MK-1 (Mark/model) tuner.
It weighs 10oz, it is threaded 1"-20TPI, and recessed ~1.5" which greatly amplifies its effect by way of mechanical leverage on the muzzle. It is designed to be adjusted and then locked in place without using any tools or screws/clamps that can potentially pinch the bore. It is made out of stainless steel which makes the maintenance as easy as little CLR on a q-tip and a paper towel. MK-1 is also very easy to use. It is adjustable in and out, and even just its added weight at the muzzle has positive impact on the accuracy. I read an article in Accurate Shooter a while back, about a guy who was using a tuner that was adjustable in several different ways. In my opinion that's counter productive, and can lead to a lot of confusion. Most top shooters I know, test one variable at a time (powder charge, seating depth etc)when developing loads. Tuners are no exception, but more about that in part two.
A 10oz tuner equals in weight 2" of 1.25"straight barrel. If your rifle weighs close to the weight limit with a 30" barrel, then you would have to go to a 28" barrel (same rifle) if you would like to add a MK-1 tuner. That's an extreme example , since most rifles make weight with 31" barrels and heavier tuners, but it is possible. After many different prototypes , I settled and made standard what is the MK-2 tuner. I wanted something that's just as effective as the MK-1 but lighter.
The MK-2 weighs 7.5 oz, but adds only ~3oz to the total weight of the rifle. That's due to the tuner being the same size as the barrel (1.25" OD) and the only added weight is the recessed portion of the tuner which is ~1.25". For example, if a 31" barrel without a tuner weighs 10lbs. The same barrel machined for MK-2 tuner with it installed, will weigh 10lbs 3oz.
MK-2 works great on small bore rifles, F-TR, benchrest riggs, and it is just as effective as the MK-1 in F-Open Class. As I mentioned earlier, size does matter. That's why I offer custom versions of both, the MK-1 and 2 models (MK-1C and MK-2C). Heavier tuners have much more leverage, which is sometimes needed on shorter or thicker barrels. There certainly is a ratio between barrel OD and weight at the muzzle as far as effectiveness is concerned. I don't have the formula or math worked out, but can tell you based on years of using tuners that if the weight of a tuning device, is equal or is less then the weight of a mirage band, unless you have a barrel with a quarter inch contour, you are wasting your time. That tuner is just an accessory it doesn't do anything, and that's a fact.
MK-2C, 10.5 oz
PART TWO: APPLICATION
You have done your research, and purchased a tuner, now what? As I mentioned previously, having a plan and clear goal is crucial if the tuner is to be utilized to its best potential. There are many different ways in which the tuners are used, I will only share my approach.
Last year, I was part of the US F-Open National team competing at the World Championship in South Africa. On practice day, I shot at 800m and adjusted my bullets seating depth to where the rifle was shooting "deep Xs". Right after that, I went to the 100m (300m would have worked better) and with the bullets seated to where they shot best at 800m shot 3 x 3 shot groups. I had my MK-1C tuner ~1 revolution out from being up against the shoulder of the thread extension with the 0 at 12 o'clock . I always start at that position, since it is easy to remember and it allows me to go IN or OUT.
I shot one group at 0, then another at one full rev out , and a third group with two revolutions on the tuner out. The rifle shot super tight at all three settings, but the second group (one rev from 0) was a no shit one hole, and round.
That's the setting I used to shoot during the Individual World Championship matches. The rifle shot super tight vertical, I did loose some point due to the wind, but can honestly say that I had zero elevation shots during the entire match. I cleaned my rifle every day and reinstalled the tuner at the same setting.
I shot good on day one of the World's Team matches (no vertical issues) but on day two, I had a couple of 4s (nines on the US target).
On the morning of day three (last day) I went back to the 100m range before the match started and did a tuner test.
I shot the same configuration (zero, 1 out, 2 out) the groups got larger as the tuner was adjusted further out. I decided to turn the tuner IN, and lock it up against the shoulder and shot a three shot group. Bingo, the rifle was back in tune. I shot a five shot group to confirm the setting and the rest is history , we won the Gold medal.
My ammo was loaded several months before the start of the competition. Besides adjusting the seating depth, and the tuner I had no other way of altering my ammo in pursuit of better precision. There's no doubt in my mind that the 11.5 oz KMR MK-1C I used, saved the day and turned what could have been 20 days of frustration to a Gold medal.
My normal routine for new barrels, new lot of powder, bullets etc is as follows: I load in in groups of three, half a grain apart nine rounds total. I have a pretty good idea what powder charge will perform best in my wildcats, so I only test .5gn up or below that. For example, my 284 KMR match load is 51.5gr of RE16 so I will test 3x51gr, 3x51.5 and 3x52gr.
I will shoot a ladder test at 1000 yards with the tuner at 12 o'clock zero. I will shoot two or three more ladder tests, adjusting the tuner one full revolution out. My goal is to find the setting that "shrinks" the ladder with everything else being equal. From that point on, I do the rest of my load development changing one variable at a time leaving the tuner at the optimal setting.
Yet another way of using a tuner is:
I have noticed throughout the years of traveling to different range locations, that a load that shot tight in my home state, did not always perform as well in a different location.
I will use the South West Nationals competition in this example.
On practice day (Thursday) I will adjust the tuner at the 800 yard line. I will do the usual, start at 0, 1 rev out etc. plotting my groups on a piece of paper. At 900 yards, I will fine tune. For example, if the rifle shot best at two revolutions out, I will try half a rev in and out. At 1000 yards I will shoot 15 shots to confirm the 900 yard results. During the competition , I adjust the tuner quarter of a turn in on match one if it is cool, and the same ammount out when the temp goes up. Basically, I am trying to slightly speed up and slow down the barrel vibrations, maintaining the tune of the rifle. That's a tip I received fro John Myers a long time ago.
If testing at long range is not possible, I would do the same routine but at 300yards.
Those are actual groups I shot at 300 yards. I was fire forming 300KMR cases, I was not shooting my match load, but the target illustrates the effect MK-1C has on precision.
ATS means against the shoulder, all groups are five shot, unless marked different. Notice the group at 2 revs out, that's what I look for . The rifle shot actually good without a tuner (very last group). Group #11 the lock ring was left loose, notice the vertical group the rifle shot. If you have anything heavy enough to affect the harmonics attached to your barrel, you don't want it to vibrate separate from the or you will get vertical groups.
Above is an actual target I shot last year at the Colorado Small Bore championship. I adjusted my MK-2 tuner on SS1 target (sighting shot target) and shot a perfect 200x20x on the record targets. I made the same tuner adjustments (start at 0, one rev out etc)
One of my 100 yard targets, from the same comp. My 50 yard tuner setting shot good at 100 yards, so I jus left it there.
Whether adjustable or not, the added weight of a tuner at the muzzle, does have a positive impact on accuracy. My Palma rifle shoots better groups with the front sight on than without it. My tactical rifle shot tighter with a Magneto chronograph than without one.
Tuners can extract the max precision out of your rifle, and also allow you to do something about a rifle/load that has gone out of tune. I will use again the world championship for example. I spend tremendous (for me)amount of money to prepare and attend. I was surely glad that my tuner turned my rifle from pretty good, to winning a Gold medal at the Worlds good!