Dissection of a 20ga Truball load w Pics

[cpileri]

Worthy Sirs and Ma'ams!
Still on my quest for the elusive slug that is accurate in my 20ga not-slug-gun, I took apart a 3 inch federal Truball load, which seemed to show some promise inmy testing, to see what might make it tick.
Here are the results.
First, the cut-away:
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[cpileri]

Inside the roll crimped hull, was a .604" lead foster slug with white plastic ball shoved up inside the hollow base. Together, the slug and ball weigh 336gr.
You can also see that the slug has a line crimping the ball into place. i had to destroy the slug to get the ball out to measure it.
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[cpileri]

The ball is just a 5-ish grain white plastic (dont knwo what kind) ball, .442 in diameter.
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[jmort]

TruBalls seem to shoot well in general. Most users love them. Thanks for sacrificing a slug for the cause.

[cpileri]

the wad is a very hard, not easily compressible like some other wads are though it does have crush zones, single piece w a very VERY deep cup over the powder, and a little divet at the top where the ball sits.
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[cpileri]

cup base
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[cpileri]

divet
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[cpileri]

And rthen there was 35gr of round flake powder.

just for grins, i measured the wad; .6225 which is exactly the bore diameter of my not-slug-gun!

Maybe this is it: if the ball-slug bumps up from .604 to bore size, and the wad is already bore size; that explains the sort-of OK accuracy the 2.75" ones showed.

Or, maybe I just found the perfect wad to use in some OTHER slug load- not that its very cost effective to dissassemble a factory truball just to get at a wad.

I still want a bore-size slug. I'm still on the search for accuracy w this smoothbore 20!

Hope this was interesting.
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[dverna]

What is the function of the ball? Is it only a marketing tool. If not, how does it contribute to accuracy?

Don Verna

[GBertolet]

My understanding is the reasoning is two fold. First the ball acts as a wedge, forcing the sides of the slug outwards, making a possibly undersized slug fit the bore snugly. Secondly, no pieces of wad material can be driven up inside the hollow base of the slug.

[bikerbeans]

C-,


Did you get a hold of Accurate to make a mould for the plastic balls?:kidding:

Thanks for the great pics and narrative on the slug. I have never shot a truball slugs but I have seen many post they work well in a smoothbore SG. Maybe Federal has done something for function and not marketing?


BB

[cpileri]

No, I sure didn't. "If i go w my own plastic balls, and I do have an idea; I will hit the sources mentioned in this thread:

http://castboolits.gunloads.com/showthread.php?218880-Acetal-ball-in-base-of-forster-slug

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[turbo1889]

An additional function of the ball is that it is a structural support that keeps the slugs hollow skirt from collapsing and distorting under the pressure of firing when there is massive force pushing up from the bottom to push the slug down the bore and the slugs inertial mass in the front resists the movement and the hollow skirt of the slug is under tremendous structural compression loads and especially with a thin soft skirt can collapse and distort. Ball in the center takes the force from below and transfers it up to the slugs forward body via. the bottom of the hollow base so the stress (or not all of it) is on the slugs skirt.