Bullet Stabilization Questions

[4mesh063]

Well guys,

I'm a little surprised that with the amount of shooting you do you haven't heard of anyone trying that. One person even made a completely round based bullet and shot it backward to see what happened.

Again, I have no first hand experience but since I've heard this so much from so many people, I assumed that if you made your own bullets, you had to try this for some reason or another. I just figured everyone did it!

BH, if I told you who one of the people was, you'd probably fall over.

 

[Brent]

Phil,
Do you suggest I download when I try a few?
Or does 3200 fps and the 210 JLK sound okay? Tomarrow would be a good day to experiment.

 

[4mesh063]

Brent,

in the case of the person I talked to the most about it, He shot alternating shots and was shooting for group like that so I guess it wouldn't make much difference what you did.

Now that you mention it, I think I'll give it a try today myself.

 

[4mesh063]

OK Brent,

at least in my case, they seem to be stable. I chose to shoot a 14 twist 22 with 55gr Ballistic tips.

I loaded 10, 5 backward and shot them alternatingly.

The right ones impacted where they should and grouped normally. The backward ones grouped somewhat bigger, about 70% it appears and impacted low of the normal ones but dead verticle. This at a range of 110 yards. The pressure seems the same forward or backward (just looking at the primers), but the gun reacted different. It was as if the acceleration was quicker with the backward ones and the recoil greater. The difference was slight.

At first I thought they were complete misses. My forward shots were where they should be and there was no hole visible. Then after 3 of em, I saw the holes were punched clean and could see the light through the homosote backer where it had been punched clean out. Pretty neat.

As for what I learned... My ammo looks nicer with the ballistic tips out the front!

 

[Brent]

I kind a spaced it out this morning and didn't get any loaded up backwards and I'm ready to walk out the door now. Next time I guess.

Your test is interesting. Did any go through sideways?

 

[4mesh063]

No Brent. And for what its worth, the conditions were about as nice as I've seen this winter. I even put out a wind flag though I don't know why. The sky was calm today. Only problem I had is it's cold here. Not like where you live in the tropics! It was about 5 here this morning and I couldn't set up in the living room so I HAD to go outside to do this! Brrr.

 

[davewilson]

when bullets exit a gun they are corkscrewing through the air in a circular patern.a yaw force is put on it from the spinning (torque) and it takes a while to "go to sleep".that is the center line of the bullet will be identical to the centerline of travel.did you ever take a gyro and yank the string out of it making it spin real fast.when you set it on the floor,it rotates in a circular pattern.the circles get smaller until it stayes in one spot,or nearly in one spot for a while,then it starts circling in a bigger and bigger pattern until it falls over.this is exactly what bullets do. put your gun on your best rests and shoot a group at 30 yds.i'll bet the group's at least an inch,and the "group" will be a circle,not a cluster.the longer the bullet is per caliber,the farther it will take to go to sleep.
as far as shooting worse,obviously the farther you shoot,the harder it is to hold whatever level of accuracy you and the gun can hold.when a gun shoots well,and then goes to h___ at a certain range,it's usually a stabilization problem.most paper punchers only spin the bullet fast enough to stabilize it for the distance they shoot.as it slows down its rpm's are slowing also and it becomes unstable.(wakes up)if you're hunting,you need around 50% higher rpm's for terminal performance.this is what keeps a bullet driving through an animal in a straight line.

 

[JR]

good stuff whitetail,

When a bullet pushed thru the barrel, forces tend toward centre of pressure, which is ahead of the centre of gravity of the bullet..As the bullet leaves the muzzle, it exits at a certain angle of yaw, whic is due to the muzzle pressures, and the fact this bullet is not rotating on it's centre of gravity yet..When the bullet gets out of the barrel, the spin rotation draws from the centre of pressure towards the bullets actual centre of gravity, which makes it a bit wobbly at first, but brings itself to stabilization...


JR

 

[MAX]

Meichele, don't take my testimony to court on this but my understanding of the BC/GS issue you raised is this: High GS degrades BC somewhat because of Yaw of Repose. YoR is magified by high GS. Benchresters like slow twists, or minimum twists because it minimizes bullet deformation thus improving accuracy. YoR does not really become a consideration at 100-200 yards. Generally speaking you need a high BC for effective long range shooting so that you may keep the bullet supersonic, but most bullets with this characteristic require fast twists, or large caliber. It is a vicious circle.

[ 02-20-2004: Message edited by: MAX ]

 

[canjaeger]

wow guys what a topic alot of good points i'm going to reread all you're posts for i have a problem .i have embarked on a program to see how far i can accurately shoot the hornady 150 grn fmj. the cartridge is made up of ww primer,remington case 39.5 grains of wc 845 which is to be loaded as h335 - one half grain col. is 2.8 max for magazine.so far out of my rem.vls 308 @100,200,300 meters .75moa but out to 400 they go through the target sideways

the primer says i am well bellow max preasure hence velocity will be low. in the lee book the load should be aprox 2500 fts
and the powder doesn't seem to be optimal for this load as the load volume seems to be low about 75% but i have alot of it and i want to see how far it will go
what do you think

 

[Michael Eichele]

canjaeger,

You may have other problems too like a bad crown at the muzzle or a rifling that is a little shorter or longer.

MAX, I agree with you. I dont have a problem with what you just said. That was my case and point earlier. What I said before was with LR shooting in mind. But I still choose the slowest twist possible for maximizing my 1000 yard velocity. I shoot 190 SMK in a 11.25 twist in a 308. I wouldnt go any slower. I get a .564 BC out of the deal. Any slower though, and they might not make it to 1k straight in the cold sea level air I shoot in. A 10 twist for me and it degrades the BC to a point that I personally dont like. It may only be a .525 BC, heck thats not bad. But bad enough for me.

Regards

 

[dbhostler]

Anyone see the flight of the bullet when conditions are right? When standing behind the shooter, from what I've seen, the bullet flies straight as an arrow. I've never seen a vapor trail with vortices emanating from it although I guess they're there.
db

 

[Michael Eichele]

I video taped my buddies first long range kill. He was shooting 600 yards. You can see in the video, the path of the bullet. Well you can see what most call a vapor trail. I guess its really the visual air disturbance. In any event its a really cool video!

 

[dbhostler]

One of the most amazing things I have ever seen was at the home of our local gun smith. He has had a thing for large cal pistols, I think as a result of his silhouette days many years ago. I was watching him fire his 50 cal XP, a necked up 416 WBY. He was fireing some of his lead cast 500gr bullets at a trap 25yds away. He squeezed one off and I thought I was seeing things, a shiny object going down range and hitting the target. He fired another, same thing. I said Bob, I think I'm seeing the bullet in flight. He said so matter-of-factly yea when the light is right, they're easy to see. That's true but who would have thunk it. I've heard that soldiers in WWII could see and hear the large artillery shells go overhead. That must have been something to see.
db