Author Topic: .575 Big Bore Bullet Design  (Read 252 times)

steveoh

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.575 Big Bore Bullet Design
« on: December 05, 2018, 03:26:12 PM »
Chewing on a bullet design I saw:

I modified in Photoshop shop, sized up to .575 and removed a bit of bullet thinking that less friction is better.

Any ideas if such a design would work? I'm looking for a longer bullet, hollow point, but with less contact with the barrel. I call it the pile driver.



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Alan

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Re: .575 Big Bore Bullet Design
« Reply #1 on: December 05, 2018, 04:25:33 PM »
Civil engineering degree not withstanding, I am NOT a bullet designer. However... What this looks to me like, is a pellet. But don't let that discourage you, as pellets fly rather straight too, except for a bit lower BC. In any case, it is worth a try.

Refresh my memory. Let us say you want to mold some of these. Where do you buy the mold, and how much do they cost to make?
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Alan

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Nicesurprice

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Re: .575 Big Bore Bullet Design
« Reply #2 on: December 05, 2018, 10:46:36 PM »
Take the first disign.
And get a thinner core you have a winner.
In fact just enlarge a .45 maxiball.

I know why you came to the shown disign by the way.
I use the same disign for the .72 ( with the 3 edge)
Next point.
The will need a lot off speed.
Without a desent V0 they will spread passing the 50/70 m point.
The problem ?
A bad BC.
Otherwise the will make a nice sound ( like a whissle).
And sound will cost energy (nothing comes free on this world).

Grts
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rsterne

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Re: .575 Big Bore Bullet Design
« Reply #3 on: December 06, 2018, 08:40:31 AM »
For airgun use, I see no point in a small midbody, unless you are trying to reduce weight while keeping a given length.... Shortening the bullet a bit, and increasing the midbody to where it just clears the lands (eg. 0.565"), should have less drag than those big steps, IMO.... Also, the shorter LOA can get away with a slower twist rate.... Just my thoughts....

Bob
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Alan

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Re: .575 Big Bore Bullet Design
« Reply #4 on: December 06, 2018, 10:24:46 AM »
Bob, I curious about the cost of molds. I would think there is a setup charge (engineering, etc.), but overall, what does it cost to make a special, shall we say one up, example?
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Alan

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Nicesurprice

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Re: .575 Big Bore Bullet Design
« Reply #5 on: December 06, 2018, 10:55:46 AM »
For airgun use, I see no point in a small midbody, unless you are trying to reduce weight while keeping a given length.... Shortening the bullet a bit, and increasing the midbody to where it just clears the lands (eg. 0.565"), should have less drag than those big steps, IMO.... Also, the shorter LOA can get away with a slower twist rate.... Just my thoughts....

Bob


Biggest point was indeed the weight.
A Quackenbush is not a powerhouse.
I would like speed above weight.

In mine opinion the org maxiball is hard to beat.
The disign with thick core has one advantage.
You can make them without a cherry.
So a one off mold is cheap.
I think Lyman had a .58 maxiball in the past.

Btw i use a simular disign drawn by stefen for the Dragon slayer/claw.
Only with a Hollowpoint.
Lee made this disign once.

Grts.
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steveoh

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Re: .575 Big Bore Bullet Design
« Reply #6 on: December 07, 2018, 02:21:46 PM »
Ahhhhhhh, that's where I learned about the Maxi-ball mold.

I was tired of looking at code and decided to mess around with the image of that Maxi-Ball ammo. I thought that removing one of the rings or whatever it's called would reduce friction. Anyway, just messing around.

This whole bullet design world is interesting to me. I suppose given a set of variables, caliber, weight, PSI, distance of shooting, barrel length, twist rate, number of lands, etc one might be able to predict how well a bullet design would or would not perform. Surely there's enough data out there.

Bullet shape is interesting also. Why does one shape perform better than another shape beyond the nose? Other than friction, and weight why would the middle of a bullet mean squat? Does the middle of a bullet really affect aerodynamics?

Yep, I know squat about the subject but it's fun contemplating it, and casting a variety of bullets and giving them a go.
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rsterne

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Re: .575 Big Bore Bullet Design
« Reply #7 on: December 07, 2018, 03:55:55 PM »
Alan, different companies have different machining setups, and that often dictates the setup fee.... Accurate uses a single-point tool in a CNC lathe, and will do a custom design (and then include it in their catalogue) at no charge.... However, they can't do smaller than .30 cal, or less than a 0.180" Meplat, and the base of the bullet can't be smaller than 0.060" less than the largest diameter (ie only slight boattails are allowed)…. LBT also uses a lathe, but he has to make a pattern of the bullet shape from aluminum sheet that is 10X the actual size, as his "copier" lathe uses a mechanical "pantograph" linkage to cut the mould.... and he charges $300 to make the pattern.... I think Arsenal uses a CNC lathe as well, and if you can convince him that there may be a market, he often does custom designs at no charge and includes them in his catalogue.... However, he only has a fraction of the designs that Accurate make, and some requests for custom designs seem to not happen.... the .308 "Bowman" (a scaled up Lyman 257420) a case in point.... 

NOE uses an "undersize cherry", or form tool, made to the shape of the bullet, inserted into a drilled hole in the mould block, and then spiralled out to cut the bullet cavity.... Each design requires a new form tool, and they charge $300 for a custom one, provided you let them make moulds for inventory.... If you want a proprietary design, they charge more.... Since the moulds are made on a CNC mill, they can make larger caliber moulds by interpolating out the path of the cutter.... For example, one of their .224 cal. tools makes bullets in .224, .228, .243, .257 and .265 cal.... all the same length.... They can also plunge the tool shallower into the mould blocks to make a shorter, light bullet....

I have never dealt with the other companies, but my understanding is that they use a full-size "cherry", which is ground to the finished size of the bullet, and the moulds are produced in a CNC mill.... I think they pretty much all charge a custom fee, if they even do custom designs....

Bob
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steveoh

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Re: .575 Big Bore Bullet Design
« Reply #8 on: December 07, 2018, 04:02:17 PM »
Alan, different companies have different machining setups, and that often dictates the setup fee.... Accurate uses a single-point tool in a CNC lathe, and will do a custom design (and then include it in their catalogue) at no charge.... However, they can't do smaller than .30 cal, or less than a 0.180" Meplat, and the base of the bullet can't be smaller than 0.060" less than the largest diameter (ie only slight boattails are allowed)…. LBT also uses a lathe, but he has to make a pattern of the bullet shape from aluminum sheet that is 10X the actual size, as his "copier" lathe uses a mechanical "pantograph" linkage to cut the mould.... and he charges $300 to make the pattern.... I think Arsenal uses a CNC lathe as well, and if you can convince him that there may be a market, he often does custom designs at no charge and includes them in his catalogue.... However, he only has a fraction of the designs that Accurate make, and some requests for custom designs seem to not happen.... the .308 "Bowman" (a scaled up Lyman 257420) a case in point.... 

NOE uses an "undersize cherry", or form tool, made to the shape of the bullet, inserted into a drilled hole in the mould block, and then spiralled out to cut the bullet cavity.... Each design requires a new form tool, and they charge $300 for a custom one, provided you let them make moulds for inventory.... If you want a proprietary design, they charge more.... Since the moulds are made on a CNC mill, they can make larger caliber moulds by interpolating out the path of the cutter.... For example, one of their .224 cal. tools makes bullets in .224, .228, .243, .257 and .265 cal.... all the same length.... They can also plunge the tool shallower into the mould blocks to make a shorter, light bullet....

I have never dealt with the other companies, but my understanding is that they use a full-size "cherry", which is ground to the finished size of the bullet, and the moulds are produced in a CNC mill.... I think they pretty much all charge a custom fee, if they even do custom designs....

Bob

Thank you Bob, this is incredibly useful information. 
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Nicesurprice

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Re: .575 Big Bore Bullet Design
« Reply #9 on: December 08, 2018, 12:14:10 AM »
Lee made this mold once.
This disign gave a light slug with less drag.
I know the DAQ shooters did a groupbuy at LEE

Maybe it would work in .58 also.

The original snLEE. .495-222
LEE did not have this block so they advised me to copy it.
Accurate has the body disignj just ask tom to enlarge it to the sizing you want.
Otherwise.
When pellets work.
Youre the man.



Grts
« Last Edit: December 08, 2018, 05:13:59 AM by Nicesurprice »
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Alan

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Re: .575 Big Bore Bullet Design
« Reply #10 on: December 08, 2018, 03:51:09 AM »
I've never been "into" making my own bullets, but I was sort of forced into making shotgun slugs, as I was using brass shotshell casings. Obviously then, my knowledge about molds is a limited one. That you for the enlightenment.
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Re: .575 Big Bore Bullet Design
« Reply #11 on: December 08, 2018, 09:04:02 AM »
Personally, if I was looking for a proven, big bore bullet of low weight.... I would use the EPP-UG design.... It was developed in .45 cal and has spread to .30 and .35 cal, and I think larger as well.... It is not a lot heavier than a roundball, and has proven accurate in many big bores.... Here is a .50 cal version by Accurate....

http://accuratemolds.com/bullet_detail.php?bullet=50-200R-D.png

Scaled up to .58 cal it would be about 300 gr.... and could be made by Accurate at no extra cost, just the mould cost.... I can draw one up to send to Tom if you wish....

Bob
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steveoh

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Re: .575 Big Bore Bullet Design
« Reply #12 on: December 08, 2018, 09:33:28 AM »
Lee made this mold once.
This disign gave a light slug with less drag.
I know the DAQ shooters did a groupbuy at LEE

Maybe it would work in .58 also.

The original snLEE. .495-222
LEE did not have this block so they advised me to copy it.
Accurate has the body disignj just ask tom to enlarge it to the sizing you want.
Otherwise.
When pellets work.
Youre the man.

Grts

I see that Eric Henderson of Adventures Afield was organizing a buy for the 50 cal molds. I get the feeling he’s stopped casting his own. Will ask how those performed and if he’s seen a 58 equivalent. I know he used to own a .58 DAQ LA long barrel rifle. Will see what he used.

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Re: .575 Big Bore Bullet Design
« Reply #13 on: December 08, 2018, 09:48:27 AM »
I looked through my drawings, and it turns out I have already done a .58 cal EPP-UG design....



If the diameters don't suit you, I can adjust them.... I can also increase the Meplat diameter, and/or increase the LOA to increase the weight.... As drawn it is a scaled up version of the original .45 cal EPP-UG design.... Tom at Accurate can also adjust the final diameter when he cuts the mould.... If you want me to submit this to Tom so that you can order one, email me at airgunbob at gmail dot com....

Bob
« Last Edit: December 08, 2018, 10:06:25 AM by rsterne »
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tkerrigan

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Re: .575 Big Bore Bullet Design
« Reply #14 on: December 08, 2018, 10:06:20 AM »
There's a typo at the top center of the drawing, shows the wide middle groove as .592".  Regards, Tom
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