help with a bullet design

[fg-machine]

guys i am bored and have decided to start a project that has been in my mind for a few years now and i need some help .
as a machinist the concept of making the mold itself is not an issue for me and is not the help i need .

what i do need help with is in designing the bullet , i have a very basic idea in mind and have a rather crude drawing below.

what i want is simply a heeled boolit for use in a .45lc case , the heeled portion of the bullet will be .454 dia the full dia section will be .468 .
i would like a nice wide flat nose and for the boolit to weigh somewhere between 275 and 310 grains with a 20-1 alloy .
and to keep the over all lenght down i would like to keep the full dia section and nose somewhat short

my thoughts are to keep the full dia section around .250 long with a short .100 long wide flat nose

so how long to make the .454 dia heeled section and where to add in some grease grooves and will it fly or is it a dumb idea

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[NavyVet1959]

The calculations would be pretty simple for the volume of the bullet, you just need to know the density of the lead alloy.

According to the following link...

http://www.coyotesteel.com/assets/img/PDFs/weightspercubicfoot.pdf

Lead has a density of 707.96 lbs/cu-ft and tin has a density of 455.67 lbs/cu-ft.

When you say "20-1" alloy, are you going by weight or volume?

According to the following link...

http://www.texas-mac.com/Measuring_and_Using_Specific_Gravities_of_Lead_All oys.html

A "20:1 (lead/tin)" alloy has a specific gravity of 11.0574. Since water weighs 1g/cu-cm, that means that the "20:1" alloy would weigh 11.0574 g/cu-cm. Multiply this by 2.54*2.54*2.54 (i.e. 2.54 cm/in) and you get the equivalent of 181.1983214736 g/cu-in. At 453.592 g per lb, that means 0.39947424441700911832660188010371 lbs/cu-in and at 7000 gr per lb, then 2796.3197109190638282862131607259 gr/cu-in.

Since you are not using any sort of fancy nose profile that would make calculations trickier (i.e. I would have to look up the formulas for the volumes of those curves), calculating the volume of your mold is pretty straightforward. It's simply a matter of dividing the bullet into separate simple shapes whose volumes can be easily calculated and then adding up all the volumes.

The simple shapes that you have in the above drawing are cylinders and truncated cones. One way of calculating the volume of a truncated cone is just the value of the larger cone with the smaller portion subtracted from it.

Volume of cylinder: pi * radius^2 * height
Volume of cone: pi * radius^2 * height/3
Volume of truncated cone (http://www.aqua-calc.com/calculate/volume-truncated-cone): pi * height * (BaseRadius^2 + TruncatedRadius^2 + BaseRadius * TruncatedRadius) ⁄ 3

I would suggest that you plug the various sections into a spreadsheet so that you can play with the numbers until you get what you are happy with.

Also, it looks like from your drawing that you are wanting to do some sort of hollow base design with a truncated cone for the base. You will need to calculate that volume and subtract that from the total volume.

With respect to the lube grooves, you might want to consider powder coating the bullets. That will allow you to not have to put lube grooves in the bullet. Putting lube grooves in the heeled section of the bullet might not do much for lubing the barrel and putting lube grooves in the exposed section of the bullet might result in dirt becoming embedded in the lube and scratching the barrel. Maybe an alox based tumble lube would be appropriate.

Once you have the volume, multiply it by 2796.32 gr/cu-in to get the calculated weight in grains.

Hope this helps... I've always believed that it was more useful to help someone be able to find the answer themselves than to just give them the answer.

HINT:

In your design, the total volume would consist of:
1. Volume of heeled section -- VHS
2. Volume of the full diameter section -- VFD
3. Volume of the truncated cone -- VTC

Add those 3 together and you'll get your total volume -- VT

VT = VHS + VFD + VTC

VHS = pi * RadiusHS^2 * HeightHS

VFD = pi * RadiusFD^2 * HeightFD

VTC = pi * HeightTC * (RadiusFD^2 + RadiusTC^2 + RadiusFD * RadiusTC) ⁄ 3

You did not give enough numbers to come up with a single solution, thus I suggest that you plug these formulas into a spreadsheet and play around with them for awhile until you get something that looks good to you.

Also, although you made the diameter of the base of the truncated cone equal to the diameter of the full diameter section of the bullet, if you make it less, then you will be created a semi-wadcutter design and need to change the VTC formula to use the radius of the base of the truncated cone instead of the radius of the full diameter section.

[NavyVet1959]

OK... I admit it... I was bored... Here's a quick and dirty spreadsheet that I created...

http://images.spambob.net/navy-vet-1959/bullet-weight-volume.xls

[fg-machine]

why thank you sir .

so far i am with you , to an extent . so my first question is this , what do i need to open the spreadsheet , excell or Microsoft office ?

and you might have to forgive me a little here , a few months ago i had a stroke and have since then had to learn math again from 1234 on up .
but it comes back quickly , and i know how to use a calculator so i can follow along quite well once it is plainly shown to me , thank you for that .


maybe a bit of back ground might help as well , some 18 or 19 years ago i found a very nice long lever martini at a gun show .
it had everything you could want in a martini henry , nice furniture , unmolested screws and a mirror bright bore with sharp crisp rifling as far as the eye could see .
i was a happy camper when the guy handed over five boxes of some old kynock ammo after he had lightened my wallet considerably .

when i got home i sat down and gave it a good cleaning , everything seemed good to go . the next day i go out to try my luck and see if any of the old ammo would go off , two duds and a surprising wallop to the shoulder later i try to open the breach . Houston we have a problem !

not wanting to break the extractor i take my new rifle into the shop and poke out the case , and find i have a chamber that has been cut badly enough to make it unusable .
disappointed i set the rifle in the corner and just looked at it every now and then , finally a few months later i had an idea after seeing a fellow shoot his rifle with a brass adapter and a handful of .45 long colt .
a light bulb came on in my head , i made a fixture to hold the action , got the barrel unscrewed and chucked it up in the lathe and cut the entire chamber out .
i then locktited in an insert made from a short piece of an old barrel cut off and chambered it for .45 colt . i did bit of work on the extractor and had a working shooting martini again .

i wont lie to anyone and say it is a tack driver , its not . but it is a lot of fun to shoot . put a pie plate out at 50 yards and you can hit it most every time if you do your part . i also wont go so far as to say my idea of a fix is the best idea out there . what i do know is after more then a few thousand standard .45lc loads of both the smoke and smokeless variety it has been problem free .

but i still have the same problem everyone else has with the .45colt and the martini ,a very long leade and a .468 major groove dia at the chamber end .
and that is what brought us up to this point . how to improve on my unique situation .

my brain just happened to come up with the idea of a heeled bullet , why not , it works in the age old .22 , it works very well in my swiss veterlli
it might just work for me to .

[NavyVet1959]

You will need MS Excel or something similar like OpenOffice. I believe I saved it in Office97 format so that even if you had an old version, you would be able to read it. It is not very fancy, but you should be able to cut and paste more lines for what-if situations until you get something that you like hopefully. I was bored watching my stocks drop today and decided to create the spreadsheet for you in case you were math/spreadsheet challenged. :)

Around here, you are lucky to be able to see a deer of hog at 50 yards through the brush, so hitting a pie plate at that distance is good enough. :)

Where are you located?

[bstone5]

I have designed bullets using SolidWorks.
One a short plain sided bullet for use in the 357 Sig works well.
Accurate made the mold from steel so it could be used in my Master Caster machine.
I have cast several thousand of this bullet, I size to .357 and load the 120 grain bullet in the 357 Sig and 38 Special.

[NavyVet1959]

If you decide to put lube grooves in the bullet, there are a few parts of the them and you will need to decide upon the dimensions of them.

Outer Diameter -- This should be the diameter of the portion of the bullet that you will be cutting the groove into. In your example, I would think that it would be the full diameter of the bullet (i.e. 0.468").

Groove Depth -- This is how deep you want the lube groove. The inner diameter can be calculated from this.

Inner Width -- This is how wide you want the flat spot at the bottom of the groove.

Lead and Exit Taper Width -- From what I've gathered, lube grooves are seldom cut with 90 degree edges these days and instead have some sort of angle leading from the outer diameter of the bullet to the inner (bottom) diameter of the lube groove. For a 45 degree taper, you would just put assign the Lead and Exit Taper Width to be the same as the Groove Depth. Calculating the volume of the tapered section of the lead or the exit is equal to 1/2 of the value of what a cylinder would be of that width, depth, and length. If you are using the same taper on both the lead and the exit, then you would have 2 of those values, so you can just calculate one full cylinder instead of adding together 2 halves as a shortcut in the calculations.

Just for curiosity, I've drawn up bullet designs with MS Visio. It's pretty simple to do and to then use a spreadsheet to calculate the volume (and thus the weight) of the design as long as you are using shapes without complex curves in them. It's all just rectangles and triangles, so pretty simple math.

[fg-machine]

navyvet , i am in central ohio . i am not much of a hunter so this is pretty much a paper punching project .
my main goal is to try to get the rifle to shoot as well at 100 yards as it does now at 50 .
the wide flat nose is simply to make it easier to cut the mold .
and thanks to your help i am getting this figured out , i have pt some more thought into the lube grooves and i am going to sit down after dinner tonight and put
what i have come up with so far on paper .

i have also changed my mind on how i am going to cut the mold , my original intent was to just lathe bore it .
but i think i am going to make a d bit style cutter and make the mold a nose pour with a set of pins for both a solid base and a hollow base

[NavyVet1959]

Will a hollow base obturate enough to fill the bore on your rifle with the reduced diameter of a heeled bullet?

Will you need to modify your dies in order to handle a heeled bullet?

[fg-machine]

Some good questions there . I am pretty confident that the base will obturate enough to at least get a good solid grip on the rifling if not seal every thing up . Even with a solid base .

As to dies , the worst case scenario here is I have to whip up a seating die , not a big deal .
I don't have any plans on using a crimp , but if needed I'll worry about that bridge when I come to it .

[fg-machine]

it took me a little while to get back to this , the weather has been hot and i haven't been inclined to doing much .

but today was cool and breezy so i went out and made a test mold , nothing fancy i just used two squarish chunks of aluminum for the blocks
pressed in a couple alignment pins and roughly cut the slots for a handle , and then turned out a quick d bit style cutter and a rough base pin

my only goal with the test mold is to check my dimensions , sort of a test run before investing the time needed to make a proper adjustable base , nose pour bullet mold .
sometime this weekend i am going to get the pot warm put some handles on the mold and check my diameters , if they check out i'll be ready to make a proper cutter and mold

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