- This topic is empty.
-
Topic
-
frankelliott-
Replies
-
georgeafenleyiii
frankelliott
George,
Yes, it will. With the lands in contact with the .302 nose, the GC will still be about .030 above the shoulder/neck junction.The taper from the .308 band, foreward approxamates a 1 deg angle (with bumps on the flat of the bands) and the leade angle of a ’06 throat is 1 1/3 degree.
Frank
One thing that I would like to bring up about this design is the tip of the nose. I put the radi on the nose edges because I have suspected that sharpe edged, smaller meplats may be prone to deterioration at ~Mach 2 velocitys. I did a little research last week and found that at Mach2 (2240 fps at sea level), the Concord jet was producing temp increases on it’s nose of approx. 350F. They measured with sensors set all over the aircraft. The nose of the Concord has a lot of mass to soak up heat, much more than a bullet.
I believe at Mach2 + velocitys, that the sharpe edge of the lead meplats can get much hotter than that and possibly melt. Remember that the nose temp is added to the barrel friction and the hot powder gases at the base of the bullet, then add ambient temps to that. The nose can take a real beating with those temp increases plus the force that it takes to push that shock wave.
Frank
keithsharp
Frank,
Starting at the front edge of the 308 band wouldn’t it be better to use a larger radius to extend to your small bullet tip. You originally have a 1.208 radius drawn, have you tried drawing a larger radius in place of the busy looking tapered bands and bore riding nose section. This would also make this bullet a NON bore riding design…riding only in the 308 grooves (nose would be supported better by cutting thru rifling instead of riding on top). I like your idea, but maybe it can be improved. TTT
My intent with this design is three fold:
1. The nose tip shape, should be superior to sharpe edged meplats, whether the edges of the sharpe edged meplats degrade, or not. A radius is always stronger.
2. The tapered bands are designed to reduce the effort to breech seat it if someone chooses to do that, they will also fit modern throat leads, too for shooting fixed.
3. This nose radius is conservative to attract more people to it.
It increases the BC quite a bit over simular weight and lenght bullets and has about the same bearing areas for both the nose and bands.
You are one of the few that Realize the the ogive can and will support the nose for the lenght of the lands. Most people see a long ogive and just say that it unsupported and won’t shoot. The meplat diameter is also conservative and feel that with a radius it could be as small as .050 but, that’s down the road.
The BC can also be increased with length and weight but, I’ve found that trying to get a 200 gr bullet going over 2000 fps is very uncomfortable in a rifle weighing less than about 12 lb and was hoping that the 170 gr weight would be attractive for that reason.
I’ll draw up a bullet with a 5 caliber secant nose but, it will most likely be about 180 gr and see if it has any “support”
Frank
Frank here is one I edited with Windows paint. Notice the only taper is the smaller .308 front band and radius of ogive section. This would center bullet with all throat tapers. Bullet can be made longer by adding another band and more radius on nose.
It would be difficult to get an as cast round diameter of .308 on that front band? You would need to taper bump to get bullet centered better when chambered.
will the gascheck stay inside the neck on a 300 Win Mag?
yes, the 300 Win Mag has .436 from the neck/shoulder juction the the point where the throat is .308 in diameter. My original design is .420 from the GC to the front of the .308 band. From the point that the 300 Mag leade is .308 to the end of that leade, is .155 and the bullet is .15 from the front of the .308 band to the .302 point of the nose. It would be a very good fit.
Frank
georgeafenleyiii
keithsharp
timschmidt- You must be logged in to reply to this topic.