Richard, this bullet is the first priority for me. It has a short nose to minimize slumping. I
find that as I shorten the nose on bullets I have now, but going to a flat nosed punch or a
blunter radius, or both, the better accuracy I get. This design is ultimately intended to
optimize aerodynamics w/ minimal slump. This little ridge at the ogive is only 3
thousands of an inch high and has a 45 degree leading edge. Dick feels that this is very
important although it costs a very slight amount in terms of ballistic coefficient.
According to Dick, there will be a point near the ogive where turbulence must ultimately
occur (sounds reasonable), but without the ridge the point that this happens could very
slightly along the side of the bullet, causing an imbalance in friction I suppose. The little
ridge or delaminator ring would make this initiation of turbulence occur at the same point
over the entire circumference, and remove inconsistency. Sounds reasonable to me.
Dick has a pretty good track record of designing slow moving bullets like this so I think
his idea is likely to have some merit. At least, I’m willing to give it a go. Let me know
what you think.
This is the same bullet in cross-sectional diameters rather than radii.
The tip can be sliced off flat to a 0.125”(or there abouts) meplat for the
ejector pin to push against.
Richard, this picture shows the same nose but a different base. I presume
that this bullet could be made from the same point forming die, but with a
different base punch. If it can’t, so be it. I don’t want to invest too much in
this experiment, but if it’s only the price of a punch, it would be worth the
trouble to me. I have asked that the rebate be about 0.02” so that it will be
strong enough that the lip of the base punch will not deform. If it could be
thinner, so much the better, if you feel it should be thicker, that’s okay too.
With this rebated base, I think that the base punch might still be a bit fragile
given the longish straight part. It would be fine with me if it was a straight
taper from the rebate to the final base diameter. I think this would work much
better when making the actual bullet, although it might compromise the flight
somewhat.
BTW, this bullet is predicted to have a ballistic coefficient of 0.59 in a 477 gr
version. That’s more than 20% better (if true) than anything I’ve seen.
G1 Bc v s S pe ed
0 .8
0.8
0 .7
0.7
0 .6
0.6
0 .5
0.5
G1 Bc
Drag coeffic
D ra g Co e ffic ie n t v s S p e e d
0 .4
0 .3
0.4
0.3
0 .2
0.2
0 .1
0.1
0 .0
0 .5
0
1
1 .5
2
2 .5
0.5
3
1
FN c D
R N Bc
G1 c D
Gunn/Danielson Secant Paper Patch Flat Base
Secant/shank junction angle 3.5 degrees.
Boundary air delaminator .003" by 45 degrees.
Ogive radius 1.75", nose tip radius 0.15625"
547 grains when swaged from 2.5% tin/lead alloy,
Nose represents 27% of total weight
Stability Factor 2.5 with 18" twist and 1350 fps MV
3
0 .8
0.8
0 .7
0.7
0 .6
0.6
0 .5
0.5
0 .4
0 .3
FN B c
G1 B c
G1 Bc v s S pe ed
G1 Bc
Drag coeffic
2.5
Dr. Richard F. Gunn
Work #: (203) 378-3398
Fax #: (203) 377-8251
Email: rfgunn@aol.com
D ra g Co e ffic ie n t v s S p e e d
0.4
0.3
0 .2
0.2
0 .1
0.1
0 .0
0 .5
2
S p e e d (M a c h # )
S p e e d (M a c h # )
RN cD
1.5
0
1
1 .5
2
2 .5
3
S p e e d (M a c h # )
RN cD
FN c D
G1 c D
Gunn/Danielson Secant Paper Patch Boat Tail
Secant/shank junction angle 3.5 degrees.
Boundary air delaminator .003" by 45 degrees.
Ogive radius 1.75", nose tip radius 0.15625"
477 grains when swaged from 2.5% tin/lead alloy,
Nose represents 27% of total weight
Stability Factor 2.5 with 18" twist and 1350 fps MV
0.5
1
1.5
2
2.5
3
S p e e d (M a c h # )
R N Bc
FN B c
Dr. Richard F. Gunn
Work #: (203) 378-3398
Fax #: (203) 377-8251
Email: rfgunn@aol.com
G1 B c