Smoothbore issues

[LynnC]

That kicker/dimple idea is very interesting to ponder but I think I'll stick with a cylinder bore.
Learned something new......Lynn

[2ndCharter]

I know little about ballistics {end disclaimer }. What about a dimple in the ball itself? That's why they are there in golf balls. I'm not suggesting putting 336 dimples in (novel idea for a mold and I claim creative rights over it) but a few in an arc across the face of the ball might put a somewhat controlled spin on the ball. Then I would be concerned that any behavior would be reproducible.

[frogwalking]

Chuck and I had this old Belgian ML 10 gauge with a dent in the left barrel.  We tried it to see if it was more accurate that way but the blast when the segment of the barrel containing the dent blew out made him flinch and we never found where the ball hit.  Of course, once the dent was gone, we could not reproduce the shot.  (Not to mention the hole in the barrel which made even us hesitate to shoot that side again.)  He did continue to shoot the right barrel for several years thereafter,  untill one day I got tired of looking at it and sawed both barrels off below the hole.  It never was much use after that, but it really looked scarey. 

[J.D.]

Some smoothbore shooters roll their balls...musket balls between wood rasps to dimple them. The rasps raise a burr around the dimple that increases dia of the ball, in addition to the dimples carrying more lube. Don't remember if those dimpled balls are shot bare or with a patch.

Never shot dimpled balls, so I can' comment on their effectiveness.

Just kinda thinkin'...typn' out loud, so to speak...type.

God bless

[Dphariss]

Well you haven't lived til you shoot that smoothie in the matches that allow no rear sight!~!

The careless use of a copper pick grew my touchole to a 5/64 (with a little shove a 3/32nd would have gone in) started shooting low and losing 2 f out of the vent.  (bummer) Replaced the vent and chucked out the copper pick.  I only pick her now when she demands it!!  In any case I would go with the 5/64th with enough black stuff she should shoot just fine with good ignition also....Mine happens to be a 28 gauge.

Unless the copper was very hard its not going the wear a vent unless its a liner with a thin wall and its deformed by pressure.
I just spent HOURS lapping a barrel with 220-280-400 grit and its take a lot of work to change a piece of steel much I may have taken out a .001 or so. It sure is shiny now though
If you care to experiment take a piece of copper and rub it on a piece of barrel steel with all the pressure you can stand for 2-3 hours and see how much wear you produce.
GAS CUTTING is another matter and this WILL eat out plain vents and even stainless to some extent.

Dan

[joelvca]

As I understand it, it's a little "bump" somewhere in the top or bottom of bore that causes the ball....er, pellet.... to have top spin or bottom spin coming out of the bore.  Not sure (okay, can't remember) which it is.  All I know is that when he shot without the kicker the ball "knuckleballed" all over the place as velocity dropped.  You could watch it through the scope.  With the kicker at work, the ball easily doubled or tripled it's range before the knuckleballing started.  

I can't see how it could be done in a muzzleloader unless it was a dimple at the muzzle, but it sure set my lead ball thoughts on fire.  If it worked, I could easily see it being an effective "cheat" for smoothbore matches.

I recall writings by a late-18th or early-19th century ballistician concerning accuracy in firearms, among other things.  He discussed the ball in a smoothbore bouncing randomly down the bore, acquiring a different spin at each bounce, with the final spin determining which way the ball deviated.  He mentioned that some gumakers would give the muzzle of a "gun" intended for ball a slight downward bend to ensure that the ball would consistently pick up what we would call backspin.  The (more) consistent spin notably improved accuracy, and the backspin produced a flatter trajectory.  This was different from bending the barrel (further back) to regulate the point of impact with both ball and shot, and I suspect that the muzzle bend did rather bad things to to a shot load.

As is usually the case nowadays, I can no longer either recall or locate the reference.

Regards,
Joel

[northmn]

There were a lot of theories that may have sounded reaosnable back then.  If loaded properly a smoothbore does not have a ball bounding all over the place going down the muzzle.  The old "pumpkin ball" used in shot shells did, but you can now get pretty good accuracy with a modern shell by using a roundball that fits tightly in a shotcup and hence tightly patched.  The same for a tightly patched flintlock smoothbore.  Rifling puts the center of gravity or the weight if you will into the center axis of the ball such that minor imperfections are eliminated to some degree.  A smoothbore is affected by both the imperfections of weight distribution such as minute airposckets etc as well as surface imperfections.  It may not ahve helped but I did load the weapon with the parting line from the mold in the same direction.  I also got considerably more deviation horizontally than vertically.  This was consistant in all my shooting.

DP

[roundball]

Never shot dimpled balls, so I can' comment on their effectiveness.

Several years ago I bought 5 boxes of Speer .530's at a steal on EBay and the seller simply set them inside a box about the size of a shoebox, no packing material, etc.
By the time they got to me all the plastic boxes had been broken apart...500 loose balls had been banging into each other for a few hundred miles and they looked like miniature golf balls...they all shot perfectly to the 50 yards I practice at.

[northmn]

The dimpled ball would have an increased surface that may slow them down quicker.  A few sources have stated taht steel worked better than expected for shot as it had a "slicker" surface than lead.

DP

[roundball]

I think the whole idea of dimples on a golf ball is that it gives better control and lift, longer distance, etc

[JCKelly]

Dimpled golf balls presumably have less aerodynamic drag, hence keep their velocity better. At least that is my understanding of the comment by Canute, in the July 3009 topic 'Smoothbore shooters might try sanding their balls for better accuracy'  I am inclined to believe Canute.

[northmn]

Considering that everything else which is created to be aerodynamic is higly polished, and the comments I read on steel shot, I am not inclined to believe Canute.  Dimples on golf balls may make them fly more straight or some other obscure purpose, but a rough surfaced bullet will not fly faster and farther than a polished one.  Ever see dimple on the surface of a jet fighter

DP

[JCKelly]

Google "golf ball dimples" to get the answer. The site aerospaceweb.org has a detailed engineering discussion, one I might have understood about the time JFK was cavorting in the white house. It also explains why aircraft have no dimples, although newer military planes do have little vanes on the wings to do the same thing.

This numbingly detailed engineering explanation said dimples make the ball fly farther, for a given initial blow. The dimples reduce drag. Smooth vs dimpled ain't that simple.
The other thing that reduces drag on a golf ball, any round ball, is higher initial velocity. Since golfers are human & can only hit so hard, that is not an option.

But I am sure you have read in this forum that heavier powder charges, i.e. higher velocity, helps the accurate range.

And, finally, take the trouble to look over that old topic  Smoothbore shooters might try sanding their balls for better accuracy  I found it today, it was July 24, 2009. As of this morning that was page 28. Along with golf ball stuff, it discusses smoothbore musket shooters having consistently better scores (winning matches) when they rough up their balls. Either 80 grit sandpaper, or rolling over a rasp.

[northmn]

I do not want to rewrite what I wrote inDimpled Roundballs after visiting 4 sites on golf ball aerodynamics, but essentially golf balls actions depend a lot on the spin they get from the hit.  A non-spinning sphere would not have the same actions.  TOF made a good point about incresing diameter and also sometimes better shot will do something or a top shot will do something which gets everyone all excited.  After reading the articles on golf balls I think there may be something to it, but again, does a smoothbore impart spin to a ball  If so then the golf ball effect works, if not then you have as they stated increased friction.  Golf balls act like wings when spinning and get increased lift from the greater turbulence.  We also shoot at higher velocities than a hit ball which like ballistic coefficients may change things  Higher initial velocity does not reduce drag, it actually increases it, look at the Lyman catalog and understand that ball slow down quicker at higher velocities.  The main advantage of higher velocity is that the time of flight is reduced which leaves gravity less time to work on a ball.  The latest and greatest on golf balls is to place in hexagonal dimples.  Also there was mention of the "Happy Nonhooker"  which became outlawed for tournaments which was only dimpled alon a radius and left smooth on the sides.  At this time I get excellent results in my smooth rifle by loading the ball the same with the parting line up toward the sights and sorting the ball.

DP  

[Pete G.]

And, finally, take the trouble to look over that old topic.  Along with golf ball stuff, it discusses smoothbore musket shooters having consistently better scores (winning matches) when they rough up their balls. Either 80 grit sandpaper, or rolling over a rasp.

Rolling your balls over a rasp to obtain better accuracy sounds pretty drastic.....

[northmn]

I do not want to repeat what I wrote in "Dimpling roundballs"  but without the spin imparted to a golg ball when hit, dimpling roundballs is so much BS.

DP

[Daryl]

Consider we are talking about super sonic speeds - and perhaps demands and requirements that are similar to the reason jet's have smooth surfaces.  Yes- they also have small vanes to smooth the flow of air - I doubt that is even remotely similar to dimples or rasp marks.
Also - perhaps sub sonic speeds benefit from this roughness as-does a golf ball. Note also, many people shoot weak squib-type loads which are very slow indeed and at range could benefit from any help at all in accuracy.

At this time, the best accuracy I have achieved from a smoothbore with round balls, has been when those balls are travelling 1,500 fps or faster.  This is considerably faster than the speed of sound - making sub-sonic speed-fixes non-relevent.  All round balls I've shot from smoothbores have had no spin until they left the muzzle.  I have watched slow moving round balls (small, 65gr.2F powder charge from a 20 bore) vere off like a hooked or sliced gold ball - which had taken on a spin inconsistant with accuracy.

If there are any regularites on the ball, I believe they had better be consistant and evenly spaced so as to not induce a spin that causes exponentially diverting flight, as observed when balls take on a curving or hooking-type spin. A sprue sticking up above the surface, or hole from the sprue tearing out will not promote accuracy, I am sure.  This is why I think the Tanner-type moulds or rolled balls have the potential for better accuracy than balls which have a residual sprue.

[northmn]

I would like to see the whole technique of loading where they get better scores with a dimpled RB.  Also the loads.  After reading the mechanics of golf ball flight, one can expect ta ht a curve ball is the result of turbulence acting on an uneven surface.  While we try to load sprue up, we likely rarely get it perfectly centered.  That might be a cause of turbulence that could cause a hook.  I will return to the "Happy nonhooker" golf ball.  they found that with smooth sides they got less slice or hook.  That would be due to the thing taking on more of a Frisbee spin than a negative forward spin as in a Skill saw blade.  On another web site an individual discussing cast bullet defects got the same little lecture on arrow flight I gave on another thread on this site.  He thought that an arrow would go crazy if you lost a feather.  Instead, as long as they spin they tend to shoot pretty accurate, even though unbalanced.  Many inaccuracies in cast bullets are due to base deformties s in bad gas checks.  Some claim in a round ball smashing up the nose with a too tight patch ball combo can be counterproductive.  I hold with a smoothbore that does not spin, any deformity can cause problems down range as can any internal casting fault.  A rifle is can surprise you as how accurate it is with a deformed ball because the center of gravity still spins evenly around the center axis more or less canceling these effects.  In a smooth bore, the center axis and the center of gravity need to be the same.  In a perfect sphere, I wonder if spinning would matter as the turbulence should equal  out.  Look at a the old Lyman BP Handbook and the effects of turbulence on roundball.
How do you get a perfect roundball

DP

[bob in the woods]

Frankly, I don't worry about any of this. It;s a smoothbore, after all, and I can get hunting type accuracy without too much trouble. If I can keep most in 6 in at 50 Yds I take it hunting. If I really need more accuracy, I take my rifle. 90 % of all deer here are taken inside 50 yds anyway. Most I've shot were 10 to 25 yds.  When shooting off hand, most of the guys I know can't hold better than 3 to 4 inches at 50 yds anyway; and that's with a rifle with sights. Unless you put sights on the smoothbore and shoot from a rest, you've got a lot more variables working against you than an "undimpled" ball. As long as the sprue is pointing up, more or less, I don't worry about it either. Frankly, IMO, most would be better off shooting more, and armchair thinking less 

[Daryl]

 

[northmn]

Frankly, I don't worry about any of this. It;s a smoothbore, after all, and I can get hunting type accuracy without too much trouble. If I can keep most in 6 in at 50 Yds I take it hunting. If I really need more accuracy, I take my rifle. 90 % of all deer here are taken inside 50 yds anyway. Most I've shot were 10 to 25 yds.  When shooting off hand, most of the guys I know can't hold better than 3 to 4 inches at 50 yds anyway; and that's with a rifle with sights. Unless you put sights on the smoothbore and shoot from a rest, you've got a lot more variables working against you than an "undimpled" ball. As long as the sprue is pointing up, more or less, I don't worry about it either. Frankly, IMO, most would be better off shooting more, and armchair thinking less 

Mine is a smooth rifle.  A longrifle styled firearm with longrifle hardware and a smooth bore.  It has sights just like I would put on a longrifle.  Its not a fowler in that it does not balance like a shotgun, but it will work with shot and can be used very unsporting like for ground swating.  Also make a fair squirrel gun in populated areas during the off season.  So far I am doing better than 6" at 75 yards and am interested in seeing its practical range.  Just have not had time to go to the range.  I also put a vent insert in it as I had a drill bit break off in the original non vented touchhole.  Even though I got the bit removed i was getting some interesting performance with it.

DP