Poor man’s Blackout – 100gn NLG PB .225 for AR15

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Based on the initial discussion in the thread below, I am looking for interested parties to fill the list for a NOE buy if possible.

http://castboolits.gunloads.com/showthread.php?323456-Poor-man-s-Blackout-100gn-subsonic-223-Rem&p=3893396

100gn.
Plainbase.
No lube groove for powder coating.
RN/spitzer type for feeding in semiautomatic.
Specs outlined, but not finished (true cast bullet drawing and .223/Wylde chamber consideration appreciated).

This is a jacketed 100gn that I extrapolated some rough measurements from:

Topic

[Full.Lead.TacoKeymaster]

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So the idea is to make a big 223 bullet which will cycle the action of an ar15 while going at subsonic speeds?

[jonasbjork]

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The bullet should cover four uses:

1. Subsonic, 100gn jacketed has been done as subsonic in AR15. With the correct powder and charge it should be possible to replicate with cast.
2. 1600 fps for power factor 160, for competition use. Really cutting down on bullet cost at least up to 100y.
3. 2000 fps for hunting.
4. Plinking.

And of course it would be excellent at any velocity in a bolt action.
Twist rate would have to be 1:7 for subs, but above that 1:8 or even 1:10 would do fine above 1500 fps.

For my part it is the 160 PF competition loads that spawned the idea.

[Full.Lead.TacoKeymaster]

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well, I sure don’t need something like this…  but I’d be down for a 5 cavity mold just for the fun of tinkering with the different loading possibilities.  Added bonus would be the ability to use my 223 AR15 on my steel targets at closer than 100 yards with no damage.  Count me in.

[richardmorony]

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Interested, depending upon dimensions.

I don’t know about anyone else, but I’m looking for an as cast dimension of at least .2265, as cast from 50/50, minus whatever the nominal dimension of coating might be.

The lack of conventional lube groove concerns me.  For one, it eliminates any buyer who might wish to use it with conventional lube.  Second, a lube groove give a place for metal to displace to during transition into the rifling.  Location of a lube groove would probably make more sense located where the bullet will be seated in the neck as opposed to the traditional location.  Not a deal killer for me, but something to think about.

[devinfry]

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I would be fine with a lube groove, possibly round like the Eagan 30cal bullet. The groove doesn’t have to be too big.

[rsterneParticipant]

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I also would be curious where the lead displaced by the lands of the rifling goes?….

Bob

[jonasbjork]

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I own about ten no groove molds for different calibers. Never seen that lead displacement would be a problem.
Also, I am worried that to retain the 100gn weight and have a lube groove, the bullet would have to be even longer…

Normally the lead is displaced by plasmic deformation, in other words, once the bullet has obturated to fill the grooves, it gets longer.

[richardmorony]

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I must admit to funning a bit about the Plastic Deformation.  ( have had several spirited conversations about that subject and “Dirt Grooves”)

I’m a little surprised there has not been more activity for this mold,,,,

[devinfry]

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The cast version is still going to be shorter than the jacketed version. One small grease groove isn’t going to mean anything. The bullet will ahve more than enough bearing surface.

[jonasbjork]

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I’m not a machinist, but doesn’t the cherry they use to cut molds with allow the operator to do a grooveless design with a cutter that has a groove?

I feel it is time we got a drawing and some weight calculations for this bullet. Anyone have the skills and software to do it?

[devinfry]

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The groove could be removed after the cavity is cut. I’ve done it before.

[jonasbjork]

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Just to be sure, I’m talking about the operator backing the cherry out to make a NLG as ordered, not that the customer will have to start the Dremel.

[Full.Lead.TacoKeymaster]

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Disclaimer:  I am not good at using this software, but I think this bullet has the dimensions you were asking.  With WW it comes out to 108gr

Powdercoated red without the extra dimensions… lol:

[rsterneParticipant]

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Just ran that bullet through the Kolbe Twist Calculator….

http://www.geoffrey-kolbe.com/cgi-bin/barrel_twist.cgi?diameter=.225&length=1.047&nose=.286&meplat=.136&base_diameter=.225&angle=&boat_tail=&b_twist=7&secant_radius=&unit_length=inches&temperature=59&humidity=0&local_pressure=29.92&pressure=29.92&altitude=0&density=c_d&custom_density=11

Looks like about a 7″ twist will be necessary for it…. Just an FYI….

Bob

[jonasbjork]

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As I wrote about twists, I’ve calculated it to 1:7 for 1000 fps subs, 1:8 for 1600 fps competition and 1:10 for 2000+ fps hunting.

[Author]

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