THE TRUTH ABOUT BARREL MOVEMENT ???

[Alex Wheeler]

I did not mean to say that there was no horizontal movement, but just explain what generates a lot of the vertical movement. There is a lot more going on than I wrote about. You may also have a copy, but in case you do not, Vaughn's book is available for free on line. He did a lot of work with an accelerometer mounted on barrels' muzzles and an oscilloscope. For one experiment he measured the amplitude and frequency of muzzle vibration of a barrel that was part of a rail gun and then mounted weights high on the sliding part that the barreled action was part of, to bring the center of mass of that assembly to the barrel's centerline. this had a major effect on the amplitude of the muzzles vibration, reducing it significantly. On the tunability of a balanced rifle (center on mass on bore CL0) a friend has such a rifle, a short range group heavy varmint (13.5# max. wt.) and he has had no trouble tuning it to very fine accuracy, with a very broad node and less apparent temperature sensitivity.

I sold that book years ago. It was an interesting read.

 

[gunsandgunsmithing]

Would be interesting see if two barrels of similar dimensions, but one being octagon, differ in the whip factor. jd

Haven't tested one but I'm fairly sure that while you'd see a different frequency and amplitude, the end result will be similar to a more typical contour.

There's a big difference in bbl contours between say a typical sr br rifle and a typical LR br rifle. The short range lets say is a 22" LV contour and the LR rifle is a 30 inch 1.25 straight. In the end, the difference regarding using a tuner on both is about 1 mark on my tuner from extreme in tune to extreme out of tune. So it's not nearly as significant a change as you'd logically think. At least not in regard to tuning both.

 

[gunsandgunsmithing]

Its not a banana, it wanders in any way it wants to. Sometimes only part of the bore, sometimes all the way down. Fortunately how much or how little seems to have zero effect on accuracy, at least in my experience with the way I chamber. To answer your question, yes I clock every barrel.

Agreed

 

[davidjoe]

The favorite, pet question. By coincidence, I managed to shoehorn this exact question into a physics forum thread I started on time dilation regarding a satellite orbiting at relativistic speed transmitting energy via laser for 10 minutes as measured at the satellite but 30 minutes as measured on earth. The supposed 10 minute battery potential being expanded in duration was a novel thought apparently and that thread was the most active, for 2 days, some of the equations developed, and the redshift and transverse Doppler analysis being insanely eruditic.

The “one line”, unremarkable-to-anyone-else answer to this question that I fit in was this, circled below, while the participants otherwise talked in these kinds of terms.

I had already accounted for air being pushed forward, but this guy jumped right to the heart of the issue. A couple guys spent the better part of 24 hours calculating and balancing recoil from light, so…

 

[STS]

I have always thought the first movement of a barrel when fired is upward. The barrel is flexed down under its own weight, and when the vibration impulse is introduced,the barrel moves in the path of least resistance. I have included two photos of my bedding checker on one of my predator rifles that has a Light Palma taper, 22 cal, 21 inch long barrel, with a 12 ounce suppressor and cover in place. I set the dial to zero with the rifle barrel in the vertical position to eliminate the effect of gravity. Then the barrel was moved to the horizontal position. The barrel flexed approximately.023 under its own weight, and that of the suppressor. Obviously the larger the diameter of the barrel, the less deflection there will be under the effect of gravity, but it’s still present and has an effect on the direction and magnitude of travel. This rifle is very tunable for vertical at long yardage. I clock every barrel that I chamber. I do that as a result of some testing that I did with 22 rimfire barrels in my rail gun about 20 years ago.