Dimpled (Golf) Round Balls

[Bigjohn]

Well, I had to see the results to believe it. This is VERY un-traditional BUT apparently dimpled round balls fly further. Now, I might not be telling some of you something you have not tried or knew about already.

Now, before your send the men in white coats around to cart me back to the nuthouse and give me a new wardrobe (Those coats which do up at the back are all in season this year but white canvas is not my style [smilie=1: ).

The principle behind this idea is that of the Golf ball (You those white dimpled balls which people take clubs to and beat them around a course to two). It has been shown that a dimpled golf ball will fly further than a plain round smooth ball of the same weight. Apparently, back in the 1940's, Barnes WALLIS, the guy who invented the bouncing bomb of Dam busters fame found the best design for his bomb was simular to a larger version of the golf ball. It apparently bounced further and more consistently than other designs. The problem was that they could not manufacture it.:violin:

Well, back to the topic we're discussing. Someone (no I can not take credit for this idea) has tried this in a muzzle-loader with round ball and guess what? It WORKS! :drinks:

The process is simple and simular to the method used to roll the sprue cut off. One local shooter had a piece of glass which came from a fridge shelf and has a reverse dimple (Pimple) and he rolls a number of round ball between two pieces of this glass which presses the dimples into the surface of the round ball. :coffee:

I have borrowed his device for appling the dimples for my own testing purposes and will prepare some for my next visit to the range. I only have access to a .40 cal and a .75 smoothbore both flinters. I will try the .40 cal first.

I have seen some results from shots fired recently with a .45 cal TC Hawkin and there is a definite difference in point of impact on target with the same powder charge and sight setting. The RB's appear to hit higher on the target than the un-treated RB's. Groups are about the same or slightly better but will need further testing to confirm this. I will put it over the ROCK Rest. :Fire:

Note: at present I am unable to post photos of the device, targets or round ball as I am maxed out in what is allowed on this forum. If someone wants to post them for me I would have to email out the photo's to them.

:castmine:
John

[PAT303]

Big john I read about dimpled balls somewere and told one of the guys in our club about it at our regular shoot and he tried it in a bess and won the NSW state shoot with them when normaly he struggled to keep them all on paper. He declined my idea about cutting the medal in half! PAT

[45nut]

email them to me and I would be happy to post them.

[Bigjohn]

Pat303; Yes, one of our local shooters was at a shoot, Glenrowan I believe and pick up the idea from Dick S. he has been working on the idea since he came back. He produced some targets he had shot at the club recently showing the difference in grouping centres.

45NUT I will upload the photo's tonight and send tomorrow. At this time I have not shot them for myself so targets will be forthcoming later.

Apart from the ballistics side of the argument, I think it would be interesting to find at what is actually happening.

John.

[Blackwater]

As I've always understood it, dimpled golf balls fly further because of the BACKspin. The pressure differential created by the dimples going forward at the bottom of the ball, and away from the target at the top of the ball, creates lift. I'm aeronautically challenged, so I'm not sure what the dimpled ball's effect would be with the spin going around the ball, rather than in line with the bullet's path. Can anyone explain this to me???

[PatMarlin]

Hmmmm....

[StanDahl]

Another technique for achieving dimpled balls - revealed to my by xxgrampa a few years back - is to gather your balls together and put them in a vibrating case cleaner, one layer deep. As they vibrate, they will peen against each other, dimpling their surfaces and possibly evening out the sprue. He says they shoot better this way too. Stan

[PAT303]

I think i'm going to have to try this. I have a very accurate .54 mountain rifle and i'm alway's trying to cast perfect balls for it, dimpling might be a winner. pat

[klausg]

Blackwater-

Now this is going back quite a few years, when I still thought I might get an engineering degree, and we won't go into how many years that is. Anyway, if we accept the premise of the dimples causing lift, it really shouldn't matter which way the ball is spinning. In the case of the RB boolit w/ dimples, if the dimples are causing lift, I would suspect that at longer ranges the windage will also be way off, direction dependent on RH or LH twist. On a much larger & slower scale, this is pretty much happens with a curve ball in baseball. Hopefully, someone who actually remembers their fluid dynamics will chime in and flame me for this admittedly flawed explanation.

-Klaus

[felix]

Klaus, you are correct! Dimples too small to cause much of a curve, or at least until the ball slows way down. Anyway, the rotation speed would need to be faster than the foward motion of the ball to see some real action, golf or baseball. A slider, as opposed to a curve, is a spinning FAST ball and is used as a sucker pitch to just slide out of the strike zone, past the end of the swung bat. Sliders are typically thrown to weaker hitters after a few normal, straight fast balls. Weaker hitters tend to hit the slower curves, unless between much faster pitches. ... felix

[tall grass]

Geeks

I can't remember what the reason is for the dimples but will make a couple guesses. a) reduces the boundery layer of the air on the outside i.e making the round ball aerodynamicly smaller or b) the seperation from laminar flow to turbulant goes around farther i.e. causing a smaller wake. I got to go look this up. Wonder where to look?

Anyway, later

Jim

[StarMetal]

Answer here on google: http://www.sciencenetlinks.com/sci_update.cfm?DocID=23

along with a bunch more saying about the same thing.

Joe

[shooter575]

I did the vibrating thing a couple years age with .684 RB in my .69 smoothie. I was just trying to remove the sprue.They were 90% gone after 45 minute run. The balls did have a slighty frosted look to them so the dimples are quite small. I never looked at them under the glass.
At the subsonic speed I shoot them [80 gr ff@ short 500 gr RB] I could find no diffrence in accuracy at 25 and 50 yd ranges we shoot. My load will keep 3" at 25 yd offhand.Works well on 4" breakable targets.I still have some and I was going to play again with though.
Some smoothie shooters I know use a file to rough up the surface [knurling] then dip in melted lube.
I know this does not really apply to you rifled patch RB shooters,But heck?

[Old Ironsights]

If you will notice, most swaged ballsare dimpled. Why? Because they are using close to BHN-7 lead and need the microfratures caused by tumbling to "soften" them up. (Or so I've been told).

Makes sense to tumble your balls to create create both the "golfball" effect (as proven by those wiley Scotts a zillion years ago) and to get rid of spru extrusions and mellow out wrinkles tho.

[Dale53]

I don't know about the rest of you but I am NOT going to tumble my balls....:mrgreen: I prefer them just like they are.

Dale53

[Flintlockrecord]

I have been using this trick for a few years in my smoothbore flintlock pistol. I use two large coarse bastard files, one held in the vise and the ball placed on top and the second one hand held on top and just roll the ball around for a few seconds. I still patch mine but a couple of mates use them naked. they are just large enough in the bore to be a friction fit. Accuracy is outstanding, about 2'' at 25 metres offhand.

[krag35]

I tried the case tumbler idea today. I haven't gotten to shoot them yet, but I did find something interesting. I visually sort every thing I cast, and rarely does a wrinkled or "bad" bullet get into the keeper pile. When I pulled the round balls out of the tumbler, they were shinier and the sprue was better than 90% gone. I did find 7 out of 100 of them that had big craters in them only thing I can figure it that these balls had voids in them and by peening together, it showed up as a crater. hopefully I won't have any unexpected fliers like I have had on occasion.
krag35

[PatMarlin]

Exposed a void. Now that's remarkable.. :drinks:

[Bigjohn]

Well, I finished my nightshift's and had planned on a bit of test shooting today BUT we are currently experiencing gale force winds. I drove to town this morning and had to hold hard into the wind all the way there and back. Had one crow which took off as I approached and he was flying backwards.

With the .40 cal Flinter I would have to hold well and truely into the wind at the range to counter the effects of the gusts around the targets. :( The target stands would have at least three points of movement in them at fifty yards also.

Tomorrow should bring a better opportunity if this weather passes to the east overnight. I'll have to slip in between the other details in tomorrows match and shoot.

It has been interesting reading the theories placed forward here as to why it does what it does.

One question I will try to answer unless someone can put forward a solution; with the different calibre round balls and using only one rolling board could one put on too many dimples?

The unit I have for my testing seems to put just the right amount on the .395" RB and maybe too much on the .715" RB. This may require a different spacing of the dimpling pattern. My tests should show some result.

John. :drinks:

[hpdrifter]

IIRC, wider shallower dimples in the golfing kingdom were superior and the less normal surface area the better.

[Bigjohn]

Well, I've been to the range and back with the flinter and the dimpled RB's.

I was limmited to shooting at 50 metres due to other range use and had my benchrest set so I could rest the muzzle on it. I fired five standard RB with sprue cutoff as from the mould. Grouped three in a clover leaf with the other two wide to the right centre of group 3" above poa.

Gave the rifle a quick clean then shot the group with dimpled RB. The centre of the group overlapped the standard RB group.

As I asked in one of my earlier posts on this subject; How much dimpling is required to see any advantage. IMO the unit I have does not apply the right amount for my calibre, possibly too much.

I will have to try some other methods to see what happens.

John.

[Four Fingers of Death]

I don't know about the rest of you but I am NOT going to tumble my balls....:mrgreen: I prefer them just like they are.

Dale53


My Dad always called it pocket billiards. :-) Mick