Roughing Up Roundballs for my 20Ga. Trade Gun

[Maven]

I'm sure many of you have read that roughing up aroundball between 2 coarse files is supposed to improve accuracy (same aerodynamic theory as dimples on a golf ball). Several months ago I did that to a bunch of Lyman .600" RB's (.601" x .604" in fact; cast of pure Pb), which took no more than 40 secs./ball and promptly forgot about them. I've tried that particular RB before, with and without a patch (.014" and .018") and never found it to be especially accurate. OTOH, a .598" RB, cast from either a Jeff Tanner or Lee Precision mold, using those same patches, shoots a much tighter "group." I.e., I'm using a Green River Forge 20ga. trade gun (Barnett copy I think), which has no rear sight...and I kind of like it that way, but one hole groups aren't likely.

Because I may want to try something a bit different for smoothbore matches on another forum, I tested those roughened Lyman RB's earlier this afternoon. I used 65gr. Schuetzen (Wano) FFFg + a thin 20ga. overpowder wad + a .018" pillow ticking patch lubed with Stumpy's Moose Snot. (That stuff is good as the bore didn't need swabbing at all!) All shooting was done @ 25 yd. with me kneeling, but with my right elbow on the bench. The result is attached below. Btw, just for giggles and grins, I also tried those "dimpled," slightly oversized Lyman RB's with an overpowder wad + lubed felt wad + thin OP wad, but they generally scattered all over the target: My gun just doesn't like "bare ball" loads.

Would I do this again? You bet, as it seems to work, is fairly quick and easy to do, and has saved me the trouble of disposing of another mold.


P.S. The "hit" @ 2 o'clock that's on the 8 & 9 rings is actually 2! And at 6 o'clock, there are at least 3 hits, possibly 4.

[varsity07840]

The idea behind the dimpled "bare ball" came from N-SSA shooters who can't use a patched ball in smoothbore competition. Using the files raises the lead making it closer to bore size and allows for more dipped lube on the ball, which is needed when shooting a ball close to bore size. Thats the reason they're more accurate than smaller smooth surface balls. You'd have to go with a ball a lot bigger than .598-.600 to take advantage of the technique.

[Edward]

Glad it works for you ,I found no difference myself and went with different lube (Lehigh Valley) and did good / Ed

[Maven]

varsity...., While that may be true, I've tried those .604" x .601" RB's, both patched, and bare several times and got much poorer results than I got today. Whether it would work on the Lee or Tanner RB's (.598" - .599) is not really an issue, as they shoot markedly better when patched than the larger, Lyman RB (roughed up) anyway. Btw, some champion smoothbore shooters rough up their RB's via files, or so I've read in Muzzle Blasts, but I suppose those spheres are closer to bore size than what I'm using.

[bedbugbilly]

Maven - interesting . . . and a nice looking target.

I'm assuming your bore is .620? Have you tried a .610 RB in it? My Fusil-de-Chasse is a 20 gauge (.620) - 42". It's been a while since I've shot it - its of fun though. I started with a .610 ball and had good luck with that size and pillow ticking -60 grains 2F. I then picked up a .600 mold to give it a try - I found the results disappinting so went back to the .610 balls. Just curious if you've tried .610 in yours and what the results were? Obviously, what you tried worked!

[Maven]

bbb, Thanks for the compliment and trust me, that grouping was ~1/3 tighter than I got with the same RB, but as cast. As for a bore sized mold, which in my case would be .615", I'd buy one in a minute...if I could find one. Ditto for a .610" mold, which I'd like to try, but haven't yet. Btw, I tried the smaller, .598" Lee & Tanner RB's with tow wads fore and aft and a hefty powder charge (110gr., then 100gr. FFg) as per Mike Beliveau's recommendation and got impressive 50 yd. groups in a way: Under 4", but 8" to 9" to the right of where I was aiming!

Btw, here's another target using the as cast Tanner .598" RB patched with .018" pillow ticking + a thin OP wad + 80gr. FFg. The distance was 25 yd.

[Ballistics in Scotland]

The idea behind the dimpled "bare ball" came from N-SSA shooters who can't use a patched ball in smoothbore competition. Using the files raises the lead making it closer to bore size and allows for more dipped lube on the ball, which is needed when shooting a ball close to bore size. Thats the reason they're more accurate than smaller smooth surface balls. You'd have to go with a ball a lot bigger than .598-.600 to take advantage of the technique.

That sounds pretty convincing. I am sceptical of any aerodynamic advantage, for groups tighten up when you are doing something you feel good about. But if there is, I can think of a couple of things that might improve it.

The dimples on a golfball are much bigger. So you could epoxy steel shot to either one or two flat surfaces, between which you would roll. Files have a directional texture, and I think it would be all too easy to put flats on the ball. So you might do better with very coarse sandpaper glued to flat surfaces.

But... There is a big difference in velocity between a golfball and a smoothbore ball. What works with one may not with the other.

[carbine]

BTW if interested Nick Lucas sells a dimpler for $15 that's works great. PM him on the N-SSA board

[Maven]

carbine, I think Nick posted a video about that in this section in either December '17 or January '18. As I don't have a drill press and didn't want to use an electric drill, I opted for rolling a RB between two coarse files.

[bedbugbilly]

Maven - LOL. . . like my Dad always said, "If it ain't broke, don't fix it!". That's a great target! Regardless of all the theories, why's and why nots, if it works, it works.

I had to chuckle when I read varsity's post about the RB and the N-SSA - and no criticism is intended at all varsity as I found the info you posted interesting. I shot N-SSA for a number of years and throgoughly enjoyed it. What always amazed me though was when I would overhear comments like "the N-SSA is the most "authentic", etc. - especially when directed towards reenactors, etc. - and I'm not saying this to stir things up - I never got in the middle of such things. It's fine to take competition seriously and I understand that. I knew fellows tho took it so seriously thought that they would actually get sick over it. They weighed out each powder charge, minieball . . spent lots of money on expensive barrels, sizers, etc. I remember one time when a team showed up with magnetic devices on their belts so they could hold their ramrods there instead of propping them up on a bayonet in the ground because they thought they could pick up "seconds" in un-needed movements - that didn't last long. LOL Taking that all in to consideration, I often wondered how things would go if everyone on the line had an "as issued" rifled musket and before the shoot, they would bring out arsenal boxes of standard loads - i.e., make everything equal - then see how the shooting went. The same with the smoothbores which became popular after I was no longer shooting N-SSA. That's why I chuckled when I read varsity's post . . . given a problem, someone will come up with a way to overcome it. I'm wondering if our ancestors ever thought of such things?

This is an interesting thread for anyone who shoots smoothbores - it's been interesting to read what you are doing Maven as it is obviously working! Keep at it!

[Maven]

Thanks for the encouragement, bbb!

[waksupi]

I didn't find much, if any difference in the roughened balls. Both the smoothbores I have at the time shoot like rifles, so what would I do with a bit more group tightener? If I am on target, they are going to hit.

[longbow]

As bedbugbilly says... if it ain't broke, don't fix it! It doesn't matter why it works if it works. However, being a curious sort, I like to know why.

My opinion only is that if dimpling does improve accuracy it does it due to closer ball to bore fit. I can say that after launching hundreds of pounds of lead balls down range from my smoothbore shotguns that the closer the ball is to bore diameter the better accuracy is.

I can also say that accuracy much beyond 50 to 60 yards becomes a bit iffy with groups enlarging exponentially most likely due to balls picking up random spins from air drag creating the "curve ball" effect like a baseball pitched with a spin on it.

So, I decided to do a bit of research after reading your post. Certainly no scientific or conclusive but interesting. Dimpled golf balls are discussed and all golf balls have dimples I understand it to reduce drag so gain distance. That appears to be the case. Some interesting info here:

http://www.furthereducationlessontra...rodynamics.pdf

which indicates that a dimpled ball leaving the muzzle with no spin should have less drag than a smooth ball. That should be pretty easy to test so I'll dimple some of my 0.662" or 0.678" RB's then try them in my 12 ga. any significant difference in trajectory should be obvious. Since the balls are loading into shotcups the surface should be protected in the bore.

Taking the less drag into consideration, now I am wondering if that might translate into less chance of random spins or at least longer flight time before a spin may develop (fast enough spin to affect flight). Once a spin develops the ball will develop "lift" on the surface rotating with air flow so will deviate flight in that direction. Prior I had assumed that a rough surface would tend to induce more spin sooner due to that rough surface but if that rough surface does reduce drag then that would be a wrong assumption. Again, should be fairly easy to test for any significant differences.

Also, according to Scientific American a dimpled gold ball has about 1/2 the drag of a smooth golf ball so pretty significant improvement in BC!

Now the difference between golf ball dimples and file "dimples"... they are truly different! Just how that affects drag is another question and harder to test. It's easy to use files or wire bristles to rough up a ball but much harder to make an evenly spaced consistent golf ball like dimpling. However, I think one could assume similar effect if trajectory is flatter when a file roughened ball is used as that would imply reduced drag.

So, lots of words for a simple thing! I guess this will have to go into my "To Do" list since RB's are still my favourite shotgun projectile. I have to think that a patched round ball from a musket will behave pretty much the same as a round ball launched from a smoothbore cartridge shotgun so results should be comparable.

Longbow

[Ballistics in Scotland]

I once had a typewriter with a golfball in it, but that is a very interesting website, with a lot of interesting information for anyone willing to read beyond "When it comes to sporting projectiles, Golf is King". I am fully prepared to believe that dimples do miraculous things to golfballs. But there are two obvious objections to the golfball analogy in firearms. As you say, if it did a considerable difference in trajectory at long ranges would be a convincing and easily obtainable piece of evidence. But I haven't heard that anybody has obtained it.

The claims made for it are an improvement in drag, lift and thus in trajectory. In golf they are concerned not with its flatness, but the place where it ends up depends likewise on drag. It has nothing to do with accuracy at the ranges people claim, or at which it makes any degree of sense to try for accuracy with a smoothbore gun.

The other is that lift depends on spin of the ball, which in firearms we are generally anxious to avoid. Other posters have described excellent practice to avoid the sort of spin we can avoid, i.e. that which arises by rolling in the bore. (We can't avoid other than by using a rifle, the spin which may arise in flight, as the ball slips out from behind a cushion of compressed air in front of it.) In golf, moreover, spin arises in a predictable direction of rotation, or ought to, due to technique and the cunningly conceived angle of the club face. (Ive never denied they take this game seriously.) It is the opposite direction to that which rolling of a smoothbore ball along the bottom of the barrel is most likely to impart, and out round bullet is, if anything, more likely to be drawn downwards. Or elsewhere, if it rolls on the side or top of the bore.

General Hatcher outlines just the opposite analogy from a baseball, in the unspinning ball which he terms the "spit ball". (It really doesn't sound at all nice, and not the sort of thing anybody would say in cricket.) He believed that a cushion of compressed air builds up in front of the ball, and at some unpredictable point in its path it slips out from behind it. This has the dual effect of producing a sort of irregular kink in its path, and imparting a roll just like a ball grazing over anything else.

Whether it is a bore or an air roll, the effect does fall into line with what that website claims for the golfball. Actually every part of the ball is moving forwards. Our rolling ball is deflected towards the side on which the surface of the ball is moving backwards relative to the other side.

[59sharps]

As bedbugbilly says... if it ain't broke, don't fix it! It doesn't matter why it works if it works. However, being a curious sort, I like to know why.

My opinion only is that if dimpling does improve accuracy it does it due to closer ball to bore fit. I can say that after launching hundreds of pounds of lead balls down range from my smoothbore shotguns that the closer the ball is to bore diameter the better accuracy is.

I can also say that accuracy much beyond 50 to 60 yards becomes a bit iffy with groups enlarging exponentially most likely due to balls picking up random spins from air drag creating the "curve ball" effect like a baseball pitched with a spin on it.

So, I decided to do a bit of research after reading your post. Certainly no scientific or conclusive but interesting. Dimpled golf balls are discussed and all golf balls have dimples I understand it to reduce drag so gain distance. That appears to be the case. Some interesting info here:

http://www.furthereducationlessontra...rodynamics.pdf

which indicates that a dimpled ball leaving the muzzle with no spin should have less drag than a smooth ball. That should be pretty easy to test so I'll dimple some of my 0.662" or 0.678" RB's then try them in my 12 ga. any significant difference in trajectory should be obvious. Since the balls are loading into shotcups the surface should be protected in the bore.

Taking the less drag into consideration, now I am wondering if that might translate into less chance of random spins or at least longer flight time before a spin may develop (fast enough spin to affect flight). Once a spin develops the ball will develop "lift" on the surface rotating with air flow so will deviate flight in that direction. Prior I had assumed that a rough surface would tend to induce more spin sooner due to that rough surface but if that rough surface does reduce drag then that would be a wrong assumption. Again, should be fairly easy to test for any significant differences.

Also, according to Scientific American a dimpled gold ball has about 1/2 the drag of a smooth golf ball so pretty significant improvement in BC!

Now the difference between golf ball dimples and file "dimples"... they are truly different! Just how that affects drag is another question and harder to test. It's easy to use files or wire bristles to rough up a ball but much harder to make an evenly spaced consistent golf ball like dimpling. However, I think one could assume similar effect if trajectory is flatter when a file roughened ball is used as that would imply reduced drag.

So, lots of words for a simple thing! I guess this will have to go into my "To Do" list since RB's are still my favourite shotgun projectile. I have to think that a patched round ball from a musket will behave pretty much the same as a round ball launched from a smoothbore cartridge shotgun so results should be comparable.

Longbow

Since NSsa dose not allow patching rpughing the balks serves 2 purpose as I see it. purpose of roughing the balls is to hold more lube and maybe a tighter fit that a over sized ball would cause loading problems. It's not for same reason golf balls are dimpled.

[Maven]

Roughing Up RB's, Part II: I returned from the range a little while ago after retesting .604" Lyman (pure lead) RB's roughed up between 2 files. (See post #1 and attached pic). Alas, today's results weren't quite as good (see pic below), which forces me to conclude accuracy with those RB's was more a matter of chance than design. In other words, roughing up RB's for use in a smoothbore doesn't do any harm, but it apparently doesn't do much good either.

OTOH, using those as cast Lyman RB's, with everything the same as described in post #1, gave some of the best results I ever got with that particular RB and was among the best shooting I've done with that gun.

A word about today's pics. The first image is of the roughed up Lyman RB target (5 shots), with one flyer off the target @ 4 o'clock and a bad hang fire (1st shot!) shown in red. The second target (9 shots) is of the as cast RB's with the same .018" pillow tick patch I always use and a thin OS card over the powder charge (65gr. FFFg).

One last comment: Both my Lee Precision and Jeff Tanner .600" RB molds ( .598" in fact) produce a bit tighter grouping than the Lyman RB does, using the same loads, patch thickness, patch lube, and a thin ~.600" Circle Fly OS wad over the powder charge: Look at the target in post #6, to see what I mean.