Tuner TECH — POI Shift with Barrel Tuner Position Changes
Have a good look at the photos below — this may be one of the most noteworthy target strings we’ve ever published. What you can see is the effect of barrel tuner position on point of impact (POI). You can clearly see that the tuner position alters the up/down POI location in a predictable fashion.
This remarkable 15-shot sequence was shot by French benchrester Pascal Fischbach using his 6 PPC fitted with a CG (Carlito Gonzales) action and a Bukys barrel tuner.
Pascal reports: “After [bullet] seating and load validation, I put the Bukys tuner on, screwing it out 10 turns. According to Carlito, the CG’s super stiff action-to-barrel fit gives a faster vibration modulus that is detrimental below 10 turns [position of the tuner].” Pascal’s procedure was to screw out the tuner 1/4 turn progressively from one shot to the next. He shot one bullet at each tuner position, with a total of 15 shots.
15-Shot Sequence with Tuner Changes
CLICK HERE to SEE Large Version of Complete Test Strip (All 15 shots in a row).
Left Half of Target Strip (shots with 1/4 rotation change of tuner in sequence)
Right Half of Target Strip (shots with 1/4 rotation change of tuner in sequence)
Pascal observed: “Note the point of impact displacement [from shot to shot] tracks clearly along a sinusoide (sine wave curve).” This is indeed notable and significant! This shows how the tuner’s ability to change barrel harmonics can alter the position of the muzzle as each bullet exits, resulting in a higher or lower POI. Pascal sent his results to Carlito Gonzales in Argentina for analysis.
Pascal poses this question to readers: “Guess which three positions Carlito recommends to try?”
Editor’s Note: While this target sequence clearly shows how tuner position can alter bullet point of impact, this, by itself, does not tell us which tuner position(s) are best for accuracy. That will require further multi-shot group testing, involving careful experimentation with tuner position (and powder charge weights). But for those folks who doubt that a tuner can make a difference on a short, fat barrel, just take another look at the photos. The up/down changes are undeniable, and noteworthy in the wave pattern they follow.
Shooting Set-up and Test Conditions:
Pascal did this test at an outdoor range under very good conditions: “This was shot at my home range, outdoors, with four Smiley flags. The range is a narrow cut in high woods. Wind was consistent with readable flags. I started testing the tuner from 10 turns out and on to 15. I recently… found a sweet spot very close to the rearmost position of the tuner, so the rigidity provided by this super long tenon (just short of 70mm) was not a reason to overlook the recommended Bukys tuning procedure.”
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Tags: Barrel Tuner, Benchrest, Bukys Tuner, Pascal Fischback, POI Shift, Precision Shooting, Ride Wave, Sine Wave, Sinusoide
So which positions did Carlito recommend?
My guess is shot 6 or 9?
So, has anyone been experimenting with “barrel-centric” bedding?
Think: A close-fitting sleeve about 6 to 8 inches long over the barrel just forward of the receiver.. This sleeve is then “bedded” into the fore-end / bolted to the chassis, etc, but the receiver “semi-floats” in the “stock; maybe with some synthetic (soft) damper pads. Reducing the length of barrel that is free to vibrate will cause that vibration to occur at much higher freqencies and smaller amplitudes.
A prime example of something along these lines, in actual service use, would be the Finnish TKIV-85 sniper rifle which is built on a Mosin Nagant action. Don’t laugh, because they have a reputation for exceptional performance.
Interestingly, When the Chinese were cooking up a replacement for the basic old AK, they came up with something called the QBZ-95. This beast is a Bullpup firing the (also Chinese-designed), 5.8mm cartridge. This is also “barrel-centric” in its design.
Other “barrel-centric” designs include the classic Patt-53 Enfield muzzle-loading rifle; no receiver at all, just the classic “Lock, Stock and Barrel” This was the start of serious, large-scale, military “long-range” shooting; 600 yds plus.
Aniher trick I saw done with light-barreled AR variants, decades ago ws to replace the basic flash suppressor with one that included an extension tube that extended clear of teh barrel and seated against the front of teh front-sight post.This was torqued up, essentially stiffening the actual barrel and damping muzzle “whip”. You could set the “tuner” to work with several ammo types; very useful., especially if you recorded the torque (and sight) settings that produced the best groupings at a particular MPI. So, instead of having to brew a special load for each of every .223 rifle in the safe, you had ONE or maybe two and tweaked the barrel accordingly.
Just sayin”…..