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jonasbjork
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.
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:
jonasbjork
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robertpedersen1
devinfry
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.
Should be possible. Especially since a couple spring passes would likely need to be done since the diameter is so small and the bullet so long.
rsterne
I would be interested in what Twist Calculator you used to obtain a 10″ twist @ 2000 fps…. Could you supply a reference, please?….
In addition to the Kolbe Twist Calculator I linked to, the JBM produces identical results…. I also checked using the Miller Twist Rule and the Greenhill, and I got the following…. all for a Stability Factor of 1.5….
Miller @ 1120 = 8.2″…. @ 1600 = 8.7″…. @ 2000 = 9.0″
Classic Greenhill Formula = 7.4″
Greenhill with Velocity Correction @ 1120 = 6.4″…. @ 1600 = 6.7″…. @ 2000 = 7.0″
Miller-Greenhill with Stability Correction @ 1120 = 7.5″…. @ 1600 = 7.9″…. @ 2000 = 9.0″Kolbe & JBM (based on the Robert McCoy “McGryo” algorithm) @ 1000 = 7.2″…. @ 1600 = 7.4″…. @ 2000 = 7.3″
Bob
This is from the Berger calculator:
Length 1.047″
Estimated BC: 0.500
Weight: 100 grainsAt 1000 fps
1:7 twist – Stable (SG 1.83)
1:8 twist – Marginally stable (SG 1.40)
1:10 twist – Unstable (SG 0.90)At 1250 fps
1:7 twist – Stable (SG 1.97)
1:8 twist – Stable (SG 1.51)
1:10 twist – Unstable (SG 0.97)At 1500 fps
1:7 twist – Stable (SG 2.10)
1:8 twist – Stable (SG 1.61)
1:10 twist – Marginally stable (SG 1.03)At 2000 fps
1:7 twist – Stable (SG 2.31)
1:8 twist – Stable (SG 1.77)
1:10 twist – Marginally stable (SG 1.13)At 2200 fps
1:7 twist – Stable (SG 2.38)
1:8 twist – Stable (SG 1.82)
1:10 twist – Marginally stable (SG 1.17)At 2500 fps (not really realistic for a plainbase, but let’s get the numbers here anyway)
1:7 twist – Stable (SG 2.49)
1:8 twist – Stable (SG 1.90)
1:10 twist – Marginally stable (SG 1.22)The hunting load discussion originated in the CastBoolits thread, and the point blank or up to 50y velocity deemed it stable.
As I said before, for me this is primarly about running it as a 1600 fps competition load within 100-150 yards and anything else from my side are just suggestions for others to explore their curiosities…
Drew up a boolit with a lube groove in cad similar to the design in the OP. Should be close to 100gr. Nose is slightly rebated to add some clearance for powdercoat.
Great work! A thought on the groove location; would not this mean it is below the case neck? I believe there would be advantages to have it in the neck area to reduce risk of lube contamination on the powder.
Will a flat nose provide feeding reliability in a AR15 or should we try for a slight roundnose?
Drew up a boolit with a lube groove in cad similar to the design in the OP. Should be close to 100gr. Nose is slightly rebated to add some clearance for powdercoat.
Great work! A thought on the groove location; would not this mean it is below the case neck? I believe there would be advantages to have it in the neck area to reduce risk of lube contamination on the powder.
Will a flat nose provide feeding reliability in a AR15 or should we try for a slight roundnose?
It may not be the most ideal to have the lube groove below the neck but they should shoot fine. If one is worried about the powder sticking to the lube just use a harder less tacky lube like carnauba red.
The metplat is large for a .223 bullet but really is not big. I shoot bullets with a .375″ metplat through my .458 socom AR15. If anyone thinks it is a problem we could reduce it some but I think it is probably ok.
The .458S is a single stack cartridge with single wide feed ramp. I own one as well and it does feed fine with very wide flat points.
On a double stack .223 however, I am concerned about a flatpoint. Especially for AR15 with double feedramps that have not been blended properly (and I believe that to be very common).
How about going something like the nose of this RCBS 55gn? (far right)
Since the nose isn’t short I feel it would probably feed in a rifle extension and an M4 extension even better. The rounds are supposed to come off th emag and hit the groove in the barrel extension. If I get time I can machine a .135″ metplat on some 77gr SMK bullets and see how they feed and shoot. Both my 5.56 ARs have rifle extensions with no blending of the upper receiver.
Here is the same design but with a smaller metplat, a .005″ larger radius and a 3 degree draft on the metplat like the Ranch Dog designs.
Full.Lead.Taco
Full.Lead.Taco
robertpedersen1
davidryan
devinfry
rsterne
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