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longrange1947 · 07-05-2015, 14:43

Trans sonic flight can be a problem due to the turbulence that can effect the bullet. This can be seen in the Ballistic Coefficient (BC) that, unlike published numbers, change through the flight of the bullet.

The BC decreases as the speed of the bullet decreases until trans sonic and it crashes. Once through to sub sonic it again climbs to the same level just prior to trans sonic or in many cases even higher.

The problems in bullet stability in some cases is not instability, but rather over stabilized gyroscopic problems. As soon as the bullet leaves the barrel the bullet becomes more and more gyroscopically stable. Reason is that while the MV slows, the spin rate does not slow hardly at all. This means that bullet is now becoming more and more like a gyroscope. And like a gyroscope, while hard to bump off its course, when bumped sufficiently it will do a radical change. The is where transonic can be a problem

Barrel de-resonators are an attempt to insure that the bullet comes out of the barrel at the exact same time in the barrel impulse. This increases accuracy. Most barrels, match barrels especially already do a pretty good job of that, but too many things can change the harmonics and change where the barrel is when the bullet exits. The De-Resonators are supposed to help fix that problem.

Biggest source of error? The shooter. Next is gun and ammo. Look at the statistical error of a .5 moa shooter, .5 moa gun, and a .5 moa ammo. Now change any one of them to 1 moa. Now change anyone of them to the normal hack shooter of 4 moa. Take a round and leave it in the chamber too long or out in the hot sun, you have induced an elevation error. Let the rifle set out in the sun to long and the top of the barrel heats more than the bottom. Top expands more that the bottom, elevation error. Get a crap gun and or crap ammo, and well, now you have errors compounded as the consistency is all over the map.

After that the biggest error, in rifle and long range, is air resistance. Be it wind, altitude, or whatever.

Still mud? I may be trying to answer is too short of a form. Let me know.

07-05-2015, 14:43	#18
longrange1947 Quiet Professional Join Date: Jan 2004 Location: Fayetteville NC Posts: 3,533	Trans sonic flight can be a problem due to the turbulence that can effect the bullet. This can be seen in the Ballistic Coefficient (BC) that, unlike published numbers, change through the flight of the bullet. The BC decreases as the speed of the bullet decreases until trans sonic and it crashes. Once through to sub sonic it again climbs to the same level just prior to trans sonic or in many cases even higher. The problems in bullet stability in some cases is not instability, but rather over stabilized gyroscopic problems. As soon as the bullet leaves the barrel the bullet becomes more and more gyroscopically stable. Reason is that while the MV slows, the spin rate does not slow hardly at all. This means that bullet is now becoming more and more like a gyroscope. And like a gyroscope, while hard to bump off its course, when bumped sufficiently it will do a radical change. The is where transonic can be a problem Barrel de-resonators are an attempt to insure that the bullet comes out of the barrel at the exact same time in the barrel impulse. This increases accuracy. Most barrels, match barrels especially already do a pretty good job of that, but too many things can change the harmonics and change where the barrel is when the bullet exits. The De-Resonators are supposed to help fix that problem. Biggest source of error? The shooter. Next is gun and ammo. Look at the statistical error of a .5 moa shooter, .5 moa gun, and a .5 moa ammo. Now change any one of them to 1 moa. Now change anyone of them to the normal hack shooter of 4 moa. Take a round and leave it in the chamber too long or out in the hot sun, you have induced an elevation error. Let the rifle set out in the sun to long and the top of the barrel heats more than the bottom. Top expands more that the bottom, elevation error. Get a crap gun and or crap ammo, and well, now you have errors compounded as the consistency is all over the map. After that the biggest error, in rifle and long range, is air resistance. Be it wind, altitude, or whatever. Still mud? I may be trying to answer is too short of a form. Let me know. __________________ Hold Hard guys Rick B. Knowledge is knowing a tomato is a fruit. Wisdom is knowing it is great on a hamburger but not so great sticking one up your ass. Author - Richard. Experience is what you get right after you need it. Author unknown.
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