Hey 44man

[Blackwater]

You recently posted that your experience has been that 2 or multi grooved bullets tended to be more accurate than single grooved cast bullets, and you weren't sure why. I was thinking about this yesterday and since I have recently tried to get back into archery with the grandboys, I began to wonder if the multiple grooves might not have some sort of fletching like effect??? I know little about the aerodynamic flow of air over the grooves in a bullet, but I know the dimples in a golf ball are the reason we can hit them so far when we get backspin on them, so even small depressions CAN, at least in some cases, have a fairly pronounced effect on a projectile's flight. If there's a single large source of turbulence, that'd be one thing, but if that turbulence (or whatever the right word is?) is spread more evenly across the parallel sides of the bullet, could it act like fletching on an arrow and stabilize it better than that of a single grease groove?

Don't think I've ever heard this anywhere, but wondrous things happen when you're "on the throne" and get to thinking.

Anyone here know about aerodynamics of bullets and its effects on grease grooves??? I don't have a clue if there'd be anything to this new "theory" of mine or not.

[Lloyd Smale]

Ive never seen a real big differnce unless im castng with softer lead. For that reason ive allways thought it was a matter of the single grove bullets usually have lube groves that go deaper into the bullet. So when you shoot they have more chance of colasping due to that narrow area. Cast a single lube grove bullet like a 421429 or a 250k out of soft lead and shoot it into somethng that will allow recovery and you will find that the bullet is much shorter and the lube grove is usually about gone. This then goes back to what 44man and I have preached for years. Any deformed bullet will not deform exactly the same every time and will have a detrimental effect on accuracy. (can you say bumping up) thats why we both tend to like harder alloys.

[44man]

Yes, I like harder alloys for accuracy and recovered boolits show no damage except for rifling marks.
I can't say it is turbulence or just boolit weight distribution. It even makes a difference at 25 yards. Things do not seem to get worse with distance, accuracy is just not as good to start with. Don't get me wrong, it is not terrible and acceptable for hunting. Taking into account my bad days, days I can't see good and everything else that affects groups, the average is always better with more GG's.
My best .475 and .500 boolits have three GG's.
I made a lot of molds with one GG but just don't use them anymore. Too bad there is no way to change them.
Thinking about archery, that has been my game forever and at one time using a Wing P2 recurve, I was able to shoot a broadhead into the bull at 40 yards with NO FLETCHING after getting it tuned. I also shot bare target arrows to 60 yards.
I worked out how to tune a compound for any broadhead in 5 minutes so they hit to the same spot as a field point with accuracy. Tried to sell it with no luck and now Easton uses my method. I can change arrow sizes in a minute with the Allen wrench.
Does it apply to boolits? I sure don't know! :veryconfu
I also developed the first lighted bow sight but it was stolen and put on the market. It happens when you are poor and can't fight back. I even had a mercury switch on my bows so the sight would light when I put the bow in shooting position. It was adjustable for angles. I still make my own.

[Blackwater]

Ironically, I just bought an old Wing Slimline Master recurve. It's 70" and 35 lbs draw wt. I fell in love with it and was wretching over what they'd want for it. Well, when they said $50, I asked if they'd take $35, and guess what? They DID! Been teaching the grandboys to shoot. The 12 yr. old wants to use his 40 lb. compound for deer this year. He's got 7 under his belt with a gun, and his Dad said, "I'm going to have to limit you to a bow or you're going to kill them all!" Who knew he'd take his Dad seriously! He's swamped with homework right now, plus ballplaying, etc., but he's a pretty darn good shot with that bow even so. Now I've got TWO generations outshooting me! [smilie=w: Couldn't be happier, too!

Where's your method of tuning compounds posted? I'd really like to read it.

[303Guy]

I've been wondering about the 'golf ball effect'. It might not apply to boolits because of the way the dimpling works. It causes the air flow to break away from the golf ball further back past it's 'equator', reducing the turbulance vortex area behind the golf ball. However, there is the 'shark skin effect' to consider. But that applies to laminar flow so not sure if it would be applicable. But why should the 'golf ball effect' not apply to cast boolits with their sharp edges all over the place?

[bowfishn]

I know it's not a cast but it has been done on jacketed

http://www.longrangehunting.com/forums/f19/army-test-new-long-range-bullet-40899/

[44man]

Ironically, I just bought an old Wing Slimline Master recurve. It's 70" and 35 lbs draw wt. I fell in love with it and was wretching over what they'd want for it. Well, when they said $50, I asked if they'd take $35, and guess what? They DID! Been teaching the grandboys to shoot. The 12 yr. old wants to use his 40 lb. compound for deer this year. He's got 7 under his belt with a gun, and his Dad said, "I'm going to have to limit you to a bow or you're going to kill them all!" Who knew he'd take his Dad seriously! He's swamped with homework right now, plus ballplaying, etc., but he's a pretty darn good shot with that bow even so. Now I've got TWO generations outshooting me! [smilie=w: Couldn't be happier, too!

Where's your method of tuning compounds posted? I'd really like to read it.

You are living life! Darn, my smilies are not working, anyone have an idea? Let me see if I can post it here. If not, E mail me and I will send it. jameswbrm@aol.com Nope, it might be Firefox, I can't attach anything either.

[cbrick]

Anyone here know about aerodynamics of bullets and its effects on grease grooves??? I don't have a clue if there'd be anything to this new "theory" of mine or not.

Read chapter 9 where this is discussed.

From Ingot to Target.

http://www.lasc.us/Fryxell_Book_textonly2.pdf

Rick

[44man]

I am up and running again. Had a virus telling me I had 52 trojans and it shut me down a little at a time until I could not open anything. It wanted me to buy a program.
My friend found it buried deep.

[dougader]

I know it's not a cast but it has been done on jacketed

http://www.longrangehunting.com/forums/f19/army-test-new-long-range-bullet-40899/

Very interesting article. Sounds like it would make a great varmint "grenade." Think of the possibilities...

[Blackwater]

Guys, that "golf ball effect," at least as I understand it, is due to the BACKspin on the ball. This means that on the bottom, the dimpled surface is actually travelling faster than the top surface is. This creates a differential in pressure, with the result that the ball is lifted by that pressure. Without dimples, a round ball won't fly nearly as far because there is no upper/lower pressure differential. The number, size and depth of these dimples affects the flight of the ball, with more dimples generally creating a longer flight with the ball landing more nearly vertically than a ball with fewer and/or shallower grooves.

With a bullet, we have a projectile that's not rotating under to over, but round and round. Thus, I can't see how dimples would do anything but make the bullet "drift" more, as though wind had blown it left or right, depending on which way it's spinning (right or left hand rifling).

However, there's a WHOLE BUNCH I don't know about this, so I've learned not to assume very much when in water that's over my head. I did great in high school physics, and love to watch that sort of thing on TV, but .... well, you know.

All I was thinking was that with two grooves to "catch" the "wind" flowing over it as the bullet made its way to the target, there MIGHT be some tendency for those two grooves to catch more wind and thus, better stabilize the bullet, similar to the way longer/wider fletching better and more quickly stabilizes an arrow.

I probably should have left off my reference to the golf ball dimples since they rotate 90 degrees from the way a bullet does. Sorry to be misleading, but I can do that when I'm all wrapped up in thought, and not paying attention to the periphera.

[44man]

Blackwater, I sent you archery stuff, let me know if you get it.
Sounds like you do like I do, sit and think, try things but have no way to explain results or prove why! :mrgreen:
You are correct about the golf ball. Without dimples they don't go as far and would also hit the ground and roll well past the green.
I tried golf but lost interest fast when the rich guys and their attitudes rubbed me wrong. Maybe the dimples should be outlawed! [smilie=1:
Same as basketball, they should raise the hoop another 10 feet! :roll:
Baseball is so boring they should show porn during a game. :coffee:
Watch an archery shoot and get bored stiff.
I like that top shot show, boy would I like to play on that range with all the crazy targets they come up with. That is the best part of the show.
I want a Gatling big time but I could never afford to shoot the thing.
Anyway, I can't explain GG's. Both boolits shoot the same as far as drop as long as they weigh the same and are shot the same velocity but there just seems to be a small edge in accuracy with more then one GG. Maybe turbulence is more from one deep groove. Pack it with a hard lube so it stays full and it might do better.