Help me design my custom foster slug

[longbow]

Good round ball loads do very well in my experience. I have shot few other slugs that do as well to 50 yards or a little further. Much beyond 50 or maybe 60 yards though groups do tend to open up. I have never tested mine in 10 yard increments to 100 yards though so can't say just how far they are consistent to.

Out to 50 yards I can usually depend on 3" to 4" groups with both round balls in shotcups or naked 0.735" ball on a hard card wad column.

I can say though that the 0.735" round balls do tend to roll into the bore because I have recovered several with skewed "belts" around their equators. A donut wad, inverted gas seal or a scoop of COW should help avoid that... as would 3" hulls in a 3" chamber I am guessing.

In general I lean towards a 0.662" or 0.678" round ball in a shotcup as they are easy to load and shoot very well. The shotcup of course eliminates any chance of rolling in the bore.

After my last range session shooting 50 slug loads from the bench I flinch even thinking about shooting them prone. Yikes!

Longbow

[Ballistics in Scotland]

Ah, that is worth knowing, about the tight and therefore belted ball rotating. But I think it would take the form of just shifting a little, and be nothing like as harmful as one that enters the outside air rotating.

It is worth considering how rotation in the air makes the ball deviate. Say the rotation is clockwise, the apparent velocity of the moving air is velocity plus speed of the rotating surface on the 9 o'clock side, and velocity minus speed of the rotating velocity on the right. This produces extra pressure on the 9 o'clock side, and the bullet deviates in a three o'clock direction. If the rotation arose from curvature of the bore (far from unknown in the musket days), the deviation is exactly the opposite of what the laymen would expect.

I think, though, the latter only happens if the ball fits the bore loosely.

In your case it would take quite a bit of force to deform lead. My guess is that a hard card wad tilted. With all that people are doing with plastic wads, you would think that a wad with a hemispherical recess could be made. With shotguns required for deer in so many jurisdictions, there is surely a demand for anything that improves accuracy. From the makers' point of view injection moulding and mould making both involve expensive tooling, but a mould is a once in a lifetime process, and wads aren't.

General Hatcher claimed that a round ball, some way downrange, slips out from behind the cushion of air which builds up in front of it. He compares it with the spit ball in baseball, but I don't quite know what that is. It sounds rather horrid. It explains why the ball's path is more hockey-stick shaped than a spinning bullet's, with a lot more deviation in the second fifty than the first.

Now to go from his authoritative diagnosis to my conjecture, it may be that that cushion induces a roll in the air, and that rifling-induced spin acts like a tiny centrifugal pump, throwing off that air to all sides equally. Single-tub washing machines used to have a wheel with only shallow ribs, and yet threw up great turbulence in the water. I think friction would do the same with a spinning bullet.

[Greg5278]

Well, if Someone wants to share the cost of testing some Lathe Turned Slugs, I might be able to Help.
I have the 773gr .729" Diameter copper slugs just waiting to be tested in a Bench Gun. I'll provide the Slugs for Tom Armbrusts Canon if Somebody else pays for the Test. His Setup takes the Human component out of the Equation, and will give the true Accuracy potential.

Greg
AKA 12 Bore

[longbow]

I've been wanting to see results from these since you e-mailed me Greg. It seems that design is pretty popular in Europe. I see you have gone the full bore route rather than sub bore in a sleeve.

What is the cost of the test?

I thought about turning some from lead but they would be awfully heavy even in sub bore size. Zinc might be a good candidate for that style of slug and produce a reasonable weight. In zinc they could be cast.

BIS:

The 0.735" round balls I recovered look as though they started out with a roll possibly from opening crimp, tilting wad, catching the edge of the forcing cone or entering the bore off center. They did not spin in the bore but rather were stopped from spinning by the bore.

As for spinning in the air, any slight roll will get worse because of uneven air flow and any distortion in the surface of the ball will cause drag resulting in a spin which will get worse and worse.

I have heard the trajectory being described as a "trombone" trajectory meaning that for the first part of the journey the ball stays more or less in line but as it picks up spin so the trajectory deviates more and more rapidly. In fact one poster on All Double Guns (IIRC) said in certain light conditions you can see the balls fly and observe the trombone trajectory.

I have never seen it but I can say that out to 50 yards balls can do very well but much beyond 50 yards things start to deteriorate quickly. Some patch ball smoothbore musket shooters do well to 100 yards and are competitive with patch ball rifle shooters. Those balls would be started out with virtually no spin if properly patched so highest chance of retaining accuracy further.

The baseball analogy is describing a thrown curve ball which has a spin intentionally put on the ball so it will change direction on its way to the batter.

Use a loose fitting round ball in a smoothbore and you can miss a 2' x 3' target at 50 yards (ask how I know).

Longbow

[Ballistics in Scotland]

Same way I know, probably, although I want it read into the record that it was somebody else's gun.

Military muskets were often very badly bored, for nobody got to look through them from the breech. I doubt if they were consistent enough in bore diameter to issue everyone with close-fitting balls. But a lot of very clever minds gave up on making anything else the ordinary infantryman's issue, until the Minié bullet came along. Even George Washington tried to make his men adopt smoothbores muskets. A lot of people forget how the eighteenth century battlefield was obscured by smoke. A battalion appearing out the smoke could fire at fifty yards, and if only one side could load and march fast enough, they alone could deliver a second volley at ten or twenty. At that range Brown Bess was as deadly as any firearm ever made.

It is possible to see a rifle bullet in flight - the old .450 target bullets in particular, but probably also .30 caliber. The snag is that it has to be an observer very close to the shooter, but not the shooter himself, and you have to train yourself. If the light is good and you know exactly where the trajectory will take it, you ought to see at least part of its flight.

[longbow]

I freely admit it was me with my gun and more embarrassingly, more than once!

Yes, smoothbore muskets are a good comparison. Not only could they have varying dimensions and bore finish as you point out, there was excess clearance left intentionally to allow fast loading even when the bore was badly fouled. Accuracy was secondary to slinging masses of lead downrange in volley fire.

I think overall ranging the enemy and lobbing big 'ol .75 cal. round balls into their midst was the goal much like clout shooting with long bow ~ get the range and drop arrows into the "herd". Getting hit by a .75 cal. round ball would most certainly leave a mark! I'll pass thanks, I have enough trouble on the butt end of a slug loaded 12 ga.

I have never seen a slug or ball in flight but I have to think that with the sun behind you and looking down the sighting line while someone else shoots you would have a good chance. It would be interesting to watch a round ball and its trajectory. Of course it could be intentionally loaded to low velocity too which would make it easier. And that is a thought I should try.

Longbow

[Ballistics in Scotland]

It would probably be easiest with the round ball, and difficult with a Forster slug, which has a rear end where the sun don't shine. Here is a device which might be of help to anyone interested in what happens to a projectile in flight:

http://www.cameraaxe.com/

It is quite ironic that the skilled bowman achieved accuracy far superior to the military musket as usually constituted. General Hanger, writing in the early nineteenth century, said that with an individual enemy at 200 yards, you might as well fire at the moon. But you would not want to stand that close to a bowman who fought at Crecy, and they brought 600,000 arrows to the battlefield, with an efficient battlefield distribution system. The snag is that it took a lifetime to make a bowman, with a bow more powerful than most modern competitive archers could draw. Sherlock Holmes would have had trouble working out the reason for their distinctive musculature.

During the Revolutionary War Benjamin Franklin advocated arming regiments with the bow, and quoted in support "our great victories against the French." That was a very interesting phrase to use, when you think about it, and evidence of how well the American Revolution fitted into the British pattern of revolts and insurrections which produced parliamentary democracy. I do no think he was talking pre-Columbian.

[00BuckOperator]

Check out A.S. molds. Website or on Facebook! They make a .729 Foster & .729 Pellet Mold. Best mold maker ever. I have a lyman foster also and it drops at .699! What a joke

[iomskp]

Have a look at Cast Bullet Engineering, I have had one of his moulds for years I use the slugs in my 12 bore rifles, they work very well

[JBinMN]

Just so ya know, before these last 2 posts, this topic last posted to on 05-25-2015, 09:07 PM.

[a danl]

don' t worry about a thin skirt if you fill the hollow as i do with beeswax that way it gives you a solid base. i also use an overshot card just under the slug to keep the next wad from sticking to the wax. also i saturate the next wad with bore butter which eliminates all leading. it's interesting how our minds keep working on how to solve all our problems