Smoothbore Accuracy Fixes

[matt denison]

visualization

Willie, you used the "V" word.

I do believe in visualization. It sounds wierd, maybe it is wierd. For me it works, I think. I do try to visualize the ball (or bullet) going r i g h t t h e r e... where I want it to go. It is more of a concentration thing that forces you to focus and ignore any distractions around you.

 

[Grandpa Ron]

I have to agree on the concentration part. Not only are some shooters trance like, they are also methodical in the way they load, prime, mount, fire and follow through.

Even the more relaxed shooters have those last few moments of concentration as they let off the shot.

I find it handy to “call my shot”. That is to focus on exactly where the sight was when the shot went off. Then I can say high right or low etc.

It helps me concentrate on the site picture.

 

[Joel/Calgary]

I've seen a number of references to and/or articles about various versions of the "tailed ball" in both cartridges and muzzle-loaders. It seems to be rediscovered or reinvented with some regularity. When done correctly, it does give the same stabilizing effect as a Brenneke or Foster/Forster shotgun slug, eliminating the random knuckle-ball spin. But it increases drag, and hence drop, and needs to be done consistently to avoid vertical stringing.

While we're at it, no-one has yet mentioned putting a downward bend right at the muzzle to produce a consistent back-spin, reducing drop and eliminating the knuckle-ball scatter. It certainly screws up shot, though, so it has only been used on "guns" (in the British usage, meaning smoothbores) intended exclusively for ball. This principle has been used for more than two centuries, the latest incarnation in Air-Soft guns.

Neither of these techniques is is as accurate as rifling but both produce better consistency than the knuckle-ball break of an unstabilized round-ball.

Oh, yeah - most of the references that I can recall to roughening the ball have them being dipped in a hard or waxy lube, sometimes to be shot over wadding with the roughening to centre the ball, and sometimes with no wadding or patching for speed-shoots.

Regards,
Joel

 

[Grandpa Ron]

At times gun ballistics is about as close to Voo Doo as you can come in this modern age. If claims have been made that a slight bending of the barrel imparts a spin to the ball, I would have to say I am from Missouri and you would have to show me. It would seem the spin would be perpendicular to the flight. But, that said, stranger thing have happened. :shocked2:

Like sprew up or down, the only real study I have seen was by the Bevel brothers and that was with a rifle. My longrifle has a 1 in 60” twist so at 1800 ft./sec. the ball is spinning 21,000 rpm. It will seek its most stable position regardless of how it starts out. My smoothie had no spin.

We all know that every gun has it’s likes and dislikes. So if someone finds success by bending their barrel or some other unusual means, I may be skeptical but I still think it is important to pass such information on.

Until someone does some high speed pictures of the ball in flight, the only way I know to test sprew position, wads vs. no wads, rough vs. smooth balls etc. is to shoot, shoot , shoot. Not exactly a bad way to find out. :wink:

 

[Joel/Calgary]

If claims have been made that a slight bending of the barrel imparts a spin to the ball, I would have to say I am from Missouri and you would have to show me. It would seem the spin would be perpendicular to the flight. But, that said, stranger thing have happened. :shocked2:

The effect of the spin from the Magnus effect is seen with golf balls, baseballs, and lots of other things. The idea in gunnery is that a bare ball is given spin by contact with the barrel (I don't know if this works as much or at-all with a patched ball) and one uses just enough bend to make the top of the muzzle the last point of contact of the ball with the barrel. It has the effects I mentioned:
- It gives the ball a consistent spin, eliminating the variability of spin from random contact with the barrel or from the knuckle-ball effect on an initially non-spinning ball.
- It orients the spin so the effects are in the vertical plane of the trajectory, with no lateral deflection.
- It produces back-spin, which gives the ball lift, and thus a flatter trajectory.
This was first seriously investigated by Benjamin Robins, and described in his New Principles of Gunnery in 1742. As cited here: "Robins also investigated lateral deflection of high-speed projectiles. He set up a series of evenly spaced paper curtains that allowed him to measure the enormous deflections of a musket ball in flight. In one test a ball measured over a range of 760 yards deflected more that 100 yards to the left. Robins identified that it was the spin of the ball that caused this deflection. In a further experiment he bent a gun barrel a few degrees to the left. Although the bullet initially moved towards the left, eventually it reversed its later direction and crossed to the right of the barrel (this effect, which can be observed in baseball and tennis balls, is known as the Magnus effect)." I don't have time right now to search for it, but I'm fairly sure I remember him specifically writing of the possibility of this muzzle-bend in a "gun" intended specifically for ball. I no longer have my references to this being used by gun makers back then, but I keep seeing references to this effect being used today in both airsoft and paintball guns.

Regards,
Joel

 

[Bon Sauvage]

Very interesting. I appreciate your post.

 

[robertdale]

I have always found that the smoother the bore, mirror polished, the more consistent the groups. I brush between shots. A snug patch and ball combo. And practice.
Have used a video camera to record and watch my offhand form.was able to correct head lifting and flinch.
Just some thoughts from an old guy.

 

[Grandpa Ron]

As Joel was kind enough to point out, people have been chasing smoothbore accuracy for quite some time. While I may be skeptical, I think it is important to note what others have done.

At this point I have my 28 ga. smoothbore hitting POA at 50 yards. My groups seem to be improving with increased loads. I am up to 75 grains of 3f or 2f, I have not decided which is better. I use a patched ball tight enough to need a short starter.

I intend to move up the charge to see if the group tightens. I was wondering what powder charge others use.

I also wondered how smooth the smoothbore has to be. Would a mirror finish be more accurate?

So many question; so little time at the range. :wink:

 

[spudnut]

In my bess a greased paper patched 735 cartridge is the ticket,Cloth patches dont seem to work in it.Now in my 69 fowler and 1717 they work best with a cloth patched ball and the paper cartridge doesnt work :idunno: