Wow, those 12 gauge bore rider will be halfway down the barrel before takeoff!

The NEf is .729 grove and .719 bore.)land dia).
If you cast cast a hard mixture. Dixie 600gr are
about 80 cents delivered. And they are hardened.
If you use plastic you only need a deprimer/primer
tool, a Mec Super sizer, and a roll crimper for
the drill press.You can get used 3/3.5"" cases for
12-15 cents from Precision reloading. new primed about
35 cents I think. Ballistic products has the Multi Hull
12ga green hull, primed for 14 cents each.Rmc will soon
be doing the 3.5" brass ones.Ed

Thanks, Ed.
I can do more than is safe with that info!
I'll be watching Rocky Mountain Cartridge.
Hot dang! I've got a .729 caliber "rifle!"

Do you have a name for the 3.5" brass-hulled slug-firing rifled 12GA?

12GANQFH: 12 Guage Not Quite From Hell?

12GAFP: 12 Guage From Purgatory?

[QUOTE]Originally posted by RIP:

Hot dang! I've got a .729 caliber "rifle!"

RIP, I am glad you have finally seen the light and realized that YOU DO NEED something larger than .510.

GLZ,
Thanks for being so polite about this. If I can't handle it and yet never reach destructive testing levels with loads, it will serve as a scattergun for small game, and I will whimp on back to more manageable things like 500A2 and .505 Gibbs.

Ed,
Dixie Slug .730-cal/730-grain Terminator slug is interesting. So is the NEI mould for a .732-caliber/835-grain slug. Is there any problem with a .732" slug in a .729" rifled barrel?
1:35" TWIST O.K. for that?

835 grains at 1400 fps in an 11-pound Ultra slug (with a Leupold 2.5X), and 24" barrel: How does that sound for starters?

That should be effective for something, but I am not quite sure what that something will be, other than just for kicks.

I think that NEI mold was for a Fosbery paradox gun that swaged the bullet to fit the bore. At least thats what they told me. Better use an alloy that shrinks a little 1:20 tin:lead. I usually dont go over .730 in cast bullets. But then again, thats just lore. Dont really know what will happen if you go that far over. Then again that alloy has to go somewhere. Probably just lead your bore like hell. -Rob

SURPRISE!

The 600 OVERKILL is just about unconditionally dart stable, if made with aluminum carrier and tungsten front! I haven't run the tungsten carbide front yet, because at first I didn't believe these results and spent a lot of time convincing myself the computer was right. But tungsten carbide instead of tungsten won't change things too very much.

But you can verify these results by hand calculator, because the geometry is so simple. Just remember that dart stability is just aft area (of the cylinder sides) divided by fore area (of the cylinder sides), and the cylinders "break" at the CG. So first calculate the CG. Then the length of the aft cylinder is from the CG back, and the fore cylinder length is from the CG to the bullet front.

I haven't run the 12Ga cases yet, but I'll bet the same thing will apply. This means that a similarly-constructed 12Ga projectile should be VERY accurate even without spin, fired from a smoothbore. COOOLL!

Who woulda thunk?

Henry22LR- very cool info. A aluminum bore rider with tungsten carbide insert might actually be no more expensive to make than a pure copper version these days. I am trying to talk to Dave Corbin about compressed powder technology. Specifically tungsten/nickel composites for the front of the copper bullet. Otherwise its a .375 tungsten carbide rod insert. Dart stabilization vs spin stabilization in the .600Ok wont matter due to the short ranges it will be used at. However the higer weight will allow for a shorter bullet fo a 900gr weight vs copper which means more powder capacity and probably improved penetration.Wonder what dart stabilization does for penetration in non-aqueous media like ele.Wonder if dart stabilization will take over once spin stabilization is lost as velocity drops.-Rob

Henry22Lr- Can you run the dart stability assuming a 1.60 inch alluminum carrier with a .4 inch long, .500 inch tungsten carbide insert? Such a bullet could be made for under $5 each.- Rob

quote:

Can you run the dart stability assuming a 1.60 inch alluminum carrier with a .4 inch long, .500 inch tungsten carbide insert?

I guess you mean in a 600 OK projectile. I will run it, but it may be a day away. I'm eat up with Dr. appointments...annual check-up time...

I think 12ga aluminum carier could be 3/4 inch
shorter than 3.25" and still be stable with slow twist. Even an inch shorter. I've shot all
kinds od slugs wit locked on light wads and
they are much shorter and still stable in
smoothbores. Ed

I have the RCBS 12-GA Cowboy dies and some 2.5" brass on the way from Midway, because it was just a click away.

Dixie Slugs' Terminator slugs, .730-cal/730-grain: Do they have a hollow base to add dart stability?

I would like to design my own slug mould for a .730-caliber/?XXX-grain Rippaloy slug with a shape like the Dixie Terminator slug.

Maybe I will be re-inventing the Dixie Terminator?

I might hollow the base and make the lube-grooved bearing surface long enough to seat .750" inside the case and another .500" above the case, then a 7-degree taper for only .250" to a big meplat FN. The short truncated-cone FN would rest in the 5-degree leade of the 3" chamber.

This would fairly well fill the 3" chamber of the NEF Ultra Slug using 2.5" brass, with 3/4" of bullet length in the case, and 3/4" of bullet sticking out beyond the case mouth. The slug will be just over two diameters long.

If the base is hollowed enough to offset the taper of the FN, it will have some dart stability too. CG forward.

Might be able to make it even longer and heavier.

A simple shape like that could also be machined from copper or brass with a big, shallow hollowpoint, lighter weight, higher velocity, grooved /banded and .729" diameter. 3/4" bar stock?

Here is the one you wanted, Rob. Were you looking for a 600 grain?

An elongated football shaped slug with an FN nose and a boattail hollowed out.

Reversible:

Shoot nose first for solid nose and a wee bit of dart stability.

Shoot base first for hollowpoint or cuppoint.

Length and weight to stabilize in a 1:35" TWIST at X velocity???

quote:

Yes I'm very familiar with long .338 bullets in 1:7 twist barrels. Remember, I don't just shoot Big Bores and have done my share of 1000yrd shooting with VLD's.

Rob, what if you started showing up at .338 matches with a smoothbore .338 shooting highly dart-stabilized aluminum-carrier tungsten tipped bullets, and won?

Wouldn't that sell a LOT of bullets and rifles?

Henry22LR-, No I wanted 900gr. May need more carbide or try 9/16 diameter carbide. Its a balance between length, weight and dart stability although that really doesnt matter in the .600 OK. Twist is 1:20 also.
Thanks for running the prg though it saves me alot of trial and error.
I have my doubts about dart stabilized bullets at long range though. At short ranges they probably are just as accurate as spin stabilkized bullets but at longer ranges I've read that accuracy suffers. certainly we will find out though.
RIP- Yeah had a similar idea. I'd just love to see aluminum carriers work because of the cost compared to brass or copper. I'm learning to work with Tungsten carbide and maybe soon powdered metal composites. I can do enough with Tungsten carbide to prove this concept out or deceide it doesnt work. So far the copper Boreriders look great and if I can get their size down just a little more it would be super.-Rob
-Rob

I love it!-Rob

You could sell these like hotcakes

This design in a 12 ga. would be the s#!t

quote:

Originally posted by Henry22LR:


Here is the one you wanted, Rob. Were you looking for a 600 grain?

The 730gr Dixie is flat based. Greg Sappington
has a flat base 870 gr. Both are heatreated
and will take any velocity.
You can mold using hard alloy and coat with
spray lube and get up to 2400 without leading.
Rob- I ran a bunch of Brenekkes with locked on
lightweight plastic wads in smooth bores
in last year and they were very stable and
none were over 2" long.That AL carrier could be
shorter to allow more powder.Ed
I

Ed- I'll start cutting once I see the darn thing work. With a Tungsten carbide insert I have no doubt it will be well stabilized.-Rob

There went the material price...

I think if I shortened the carrier, the grains at peak dart stability would decrease. What length should I shorten the carrier to?

OOPS!

The insert diameter should be 0.609 in, not 6.09 in. (0.060 inch wall thickness in insert)

Henry could you put up a chart for a
2.75 inch total length? This idea is
really interesting. Ed

I'll run it tonight, Ed. Hope it helps.

Let me know if you need more, Ed.

I think we can increase dart stability a lot if you guys can figure out a way to hollow out the solid aluminum section. Without even resorting to tungsten. But the hollowing must be inside only, so as not to affect the outside surface of the aluminum carrier…

That is what I was thinking-- shortening a little, still use heavy metal in the nose, and hollow out the base. Just a hole in the base
like .35" diameter and an inch deep, with the
2.5 to 2.75" length. That way to get good
stability in smmoth bores, and stabilty in
rifled will be no problem either way, whether
hollowbase or flat base. Also a way to get good
velocity with more room for slower powders.
Slower powders are easier on brass and make resizing easier with less damagw to the rims
we put on. Ed

A canalure?
Have a dual diameter to reduce friction?

Cool!

Why not threaded brass to mate to alluminium? easier to machine.

LOL it might be the only bullet that will float

Is anyone thinking that the bottom steel bulkhead will just get crammed up into the aluminum tube by the high chamber pressure during firing?

Well, it won’t if the tube walls are heavy enough. Sure, that would happen if the whole projectile were loaded into a hydraulic press and pressure applied. But during firing there is nothing to hold the front of the bullet stationary, like in a hydraulic press: the bullet it free to move in the barrel. The only thing trying to keep the projectile stationary is the drag on the barrel walls and the inertia of the projectile. To convince yourself, replace the steel bulkhead by brass, say twice as thick as a cartridge wall. If it blows out, double the thickness until it does not blow out. Start with light loads and work up to full CUP.

I like Ed's idea better. Maybe .25 inch hole, 1 inch deep. I think there is a point where you could be inadvertently creating a barrel obstruction should the Aluminum tube collapse/JAM before the bullet begins to move. A Bore rider design will definately help avoid that problem . The hole in the base could be threaded and a Aluminum set screw used to close the rear hole.
Getting way too complicated to easily manufacture though.
Better off deep drilling the body and boring a shoulder in the nose for the TC insert to interference fit into. -Rob

Rob, you wouldn't need to close rear drilled
hole, as I didn't when I fired the hollowbase
turned brass slugs that John made for me.
They were 750 gr with the hole and fired
out the barrel fine. And the hole was
.5" diameter. Ed

Ed- Did you use anything to stop the powder from getting into that hole? I have to say I'd prefer to not have that happen. I could see a .5 inch hole in a .729 brass bullet. Not sure I like that in aluminum.
Still quite complicated to make as you need to turn the bullet around and hold it to drill a concentric hole. I'd rather go in from the front. Remember, I'm using a automated barfeeder and speed is my friend.-Rob

I can see the advantage in making them by
drilling all the way though. Then a back
plug.And a hole all the way through would
lighten up the back as much as one drilled
in the back.For plug run a threader through.
You could drill with second step type drill,a
larger drill from front to have a step to butt the insert against. Whole job being done
with one mounting in the machine. A 1/4 inch
hole would do. I think you figure on the
insert being 1/2 inch. With that hole
the back would be light enough, maybe
2.75 inch long would be perfect. Ed

My Spanish Mauser has an "overpressure safety vent hole" drilled into its chamber, in case of too-high powder loads. Something like this could maybe be built into the back end of a test projectile, until we get more confidence in the bullet not jamming in place in the barrel...

The first op is to drill(3/8) in 6061 .750 stock aluminum but not all the way through probably to 2.5 inches for example. Next is to turn to 12 GaFH bore rider dimensions .729 driving section and .719 riding section.Note Bore rider for my rifled tube and a second version without bore rider for a smooth bore. Third is to bore the nose to interference hold a 1 inch long 5/8 Tungsten carbide insert ( .618) and finally a cut off at 2.75. All That should only take a minute or two. Lets see what that does when fired and go from there.-Rob