Maths!

Dimner

Dimner

Named Man
I need help with some advance math. I'm about 70% smurt enough to know that what I am looking for should be possible to calculate, but I have forgotten all of the 2 calc classes I took in college, and forgotten over half the trig from highschool.

What I'm looking for is the place along the nose of this bullet where the diameter is at 0.294. I don't own the bullet and this calculation will help me with my decision to purchase.

TL310-178-RF_GC_AO5_Sketch.jpg
 
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popper

Well-Known Member
Unfortunately you probably won't get a correct answer. It is somewhat alloy dependent and machining tolerance. Only way to guarantee is spec the Dia ref. from the base. Aka, put a step where you want the dia spec'd., so you can measure ti.
 
Ian

Ian

Notorious member
The problem is you can figure the point but since NOE tends to make their noses a thousandth or three larger than the drawing even with weak wheelweight alloy, trying to figure it out is a complete waste of time. Sorry.
 
Dimner

Dimner

Named Man
hmmm... I guess all it takes is a son currently going to college taking Calc 3. :headscratch:

being +/- 0.003 off is no biggie. Gives me an idea of what I'm looking for.

unknown.png
 
Ian

Ian

Notorious member
If the nose casts even .001" bigger than drawing at that point, it means you have to seat about .010" deeper. You can manipulate this stuff around with alloy and casting temperature to get what you want within reason....just beware that if you figure it to the nth degree for a contact fit and the alloy grows half a thousandth in a few more weeks after loading, you'll de-bullet upon extracting a loaded round or possibly the second live round after you fired the first and there's some carbon in the throat.

I played this game more times than I care to think and have ended up gravitating to bullet designs with either concave tapered noses or with designs like this one, loading .015-.020" off the lands for reliability.
 
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popper

Well-Known Member
If you stick to secant, tangent or other, it's easier for the CNC machine to make. I had a 185gr GC made for 30/30 and didn't put a step in the nose like the 041(?), drop the dia down to where you want and bands what you want. I have to seat deep. If I did it over I would put a step in the nose.
 
Dimner

Dimner

Named Man
Ian said:
If the nose casts even .001" bigger than drawing at that point, it means you have to seat about .010" deeper. You can manipulate this stuff around with alloy and casting temperature to get what you want within reason....just beware that if you figure it to the nth degree for a contact fit and the alloy grows half a thousandth in a few more weeks after loading, you'll de-bullet upon extracting a loaded round or possibly the second live round after you fired the first and there's some carbon in the throat.

I played this game more times than I care to think and have ended up gravitating to bullet designs with either concave tapered noses or with designs like this one, loading .015-.020" off the lands for reliability.
Click to expand...
Off the lands is where I plan to end up. And de-bullet is exactly what was happening with the NOE 311-199 I have been trying to use.

I have this Teddy Roosevelt 94 commemorative 30-30 that has basically NO throat. So all the .301 bore rider bullets out there are a no go, especially with powder coating. When the 311-199 is seated where I would like it pulls out the bullet on extraction. Steating the bullet in the case so no lands are touched, leaves a comically small amount of bullet on the exterior. And 0.300" of bullet below the case shoulder.

The calculus exercise was so I can envision what a PC bullet would need to be seated to in regards for the mold I'm considering and the no throat situation.

I have fought with this rifle off and on for the better part of 6-8 years. If I dont get it done this time, it's just going to become a 375 winchester.
 
fiver

fiver

Well-Known Member
you simply could just take the nose flat point diameter and draw a line to the larger diameter.

anyway what Ian is saying is you can calculate all you want but until you actually have the mold in hand.... you don't know what your gonna get for real from them.


just an observation.
that mold eyeballs to me to be a slightly loose slip fit for a 308 made in the 80's and 90's.
 
JonB

JonB

Halcyon member
That's a Ranch Dog design.
I had the Lee version of that mold, which is now sold, BUT, I pretty sure I have some unsized bullets cast from that mold.
I have no idea how that compares with NOE's version, but if the Nose is similar enough, it might help you on your decision?
Let me know if you want a few and I'll look to confirm I actually have some.
 
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popper

Well-Known Member
This is from a marlin 30/30, same problem. Seated just so no jamming of the lands. GC is right at the bottom of neck, PCd. About a mid range load. If I were to re-do, 31-184C (which isn't worth it as I am old) I would put a slight bevel step at the point-of-jam and drop the nose down a few thou. I used a bored out fender washer to do that and found accuracy was better (~0.6" location). Not really a bore-rider but enough to make sure bullet is centered in the bore. The grooves are there for alloy movement, not lube. If I have some left I can send a few. Oh, alloy is my standard 3% Sb, HT after PC. It's M.G. so needs slightly harder alloy.
31-184C-D.png

Scan_20220423 (2).jpg
 
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Rally

Rally

NC Minnesota
You might want to check out some of the posts on here about the Ranch Dog designs for the .30-30. One design fits the Winchesters better, and I’m guessing the nose on the bullet you posted here looks much like the bullet designed for the Marlins.
 
Ian

Ian

Notorious member
I think it might actually be the other way around. The 165 which is all radius ogive to the crimp groove is awful fat for most .30-30s but fits the stadium-throat ones just dandy and shoots itty bitty groups out of mine and others but won't even chamber in any SAAMI-spec .30-30.
 
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