Some of you may recall, I have plans for a short 470 to put in a k98, on a Rigby (or Lapua) case the so-called 12mm Maus. (Or sometimes 470 Mbogo Mdogo. )
I ran the numbers thru a Powley program, and the data was quite confusing.
I wonder if anyone with Quickload or the like would mind cross-checking for me.
Case length = 2.57", capacity = 129g water, bullet is Swift 500gr SP at 1.27" long (or choose another).
COL is 3.34" and with a 24" bbl.
Now, I'm getting 2400 fps at about 44,600 CUP, which is lower pressure than expected. This is with about 99g of H 380.
And 2300 fps at 40,650 CUP (95.8g).
And 2500 fps at just about 48,000 CUP (104g, c).
And 2600 fps at 51,700 CUP (108g, c)!

Frankly, this sounds too good to be true, so I'd love a second opinion.
Thanks for your help!!

Bwana-be, sorry i can't help with the quick load. But that sure sounds like a "FUN" rifle Good luck my friend!

THIS IS NOT LOAD DATA. IT SHOULD NEVER BE USE FOR LOADING/RELOADING. THIS IS MERELY A COMPUTER MODEL EXCERCISE

i THINK i did it right in quickload...

my results are a tad lower...

in quickload, you can run it AT a specific pressure, not to exceed, and a filling rate...

I'll include a snap shot, and it seems 414 would be the best for this particular round, velocity-wise

45000 psi
Powder filling % grains fps
Hodgdon H414 93.6 99.5 2259

50000 psi
Hodgdon H414 96.6 102.7 2333

55000 psi
Hodgdon H414 99.3 105.6 2399

60000 psi
Hodgdon H414 100.0 106.4 2416

Same powder, in a 375, reaches 2500fps with 50,000 psi...

So, it looks like 50k is only 80 fps slower than 60000, and no real reason to run higher pressure

jeffe

[ 09-27-2003, 17:58: Message edited by: jeffeosso ]

I ran your data through Load-from-a-Disk. However, I used .475" as bullet diameter. Is that correct? If not I'll run it again with the proper diameter.

Their optimal charge weight of H380 was 91.7 grains, which is 86% load density. Chamber pressure= 55,378psia or 46,474 cup. Muzzle velocity=2219fps. Figured at 70 degree temp.
The 91.7 grain charge weight applies to these powders as well: RL15, N140, AR2209, AA2700, Win760, and IMR4320.

Other powders such as Varget and H/IMR4895 had optimal charge weight as 85.3 grains which is 80% load density, gives 2170fps @ 51,711psia or 44,227cup.

Hope this info is of some use to you.

Thanks, guys.
That's much more like what I had in mind.
2400 fps @ <47000 CUP = good enough for me!
Onefunzr2, yes, .475" is correct.
I don't quite understand the "optimum load density." I've heard that in reference to accuracy; is it relevant to velocity/pressure as well?
Also, do these programs have the ability to take into account length of throat?

I'm not trying to hijack the thread but is it possible to do a .475 caliber on the .458 Win Mag case, kinda like a 470 Capstick Kurtz? I am thinking of putting it in a Mauser and using the .475 pistol bullets. Thanks in advance.
Jason

Sharp,
If i remember, I'll run a 458 win case in a 470 ne die... see what it looks like

jeffe

"...for optimum cartridge performance it is necessary to burn as much powder as the case will comfortably hold while developing a pressure that the rifle can comfortably stand. This criteria is maintained by using a loading density of 80 to 90 percent and selecting a powder type that, in most instances, produces a peak chamber pressure of around 40,000 to 50,000 psi. This pressure limitation is generally safe for modern rifles in good condition yet assures good barrel life while promoting complete powder combustion and high efficiency. Remember that the pressure calculated is only an estimated value..."
This is from their website www.loadammo.com
Check it out yourself. I found nothing dealing with throat length pertaining to any of the calculations.

I think 86% load density predicts the most accurate values with their mathematical computer model. This was just one of the results. It lists 6 load densities; from 75 to 100%

It also predicted that at 106.1 grains (100% load density) you would get 2712fps BUT at 105,987psia!! Pull the trigger on that one with a long string.

I found somewhere (can't find it again) that Powley said 86% or whatever, because that was the difference between water capacity and powder capacity, water being made of smaller particles.
The thing I was reading was saying that Powley was quite distressed in his later years that despite his efforts, folks still misunderstood that.
Anyone know the article I saw?

If that is the "case" then we shouldn't be looking for 86% density, but 100% density.

Also, in continuance of this thread, it looks like my cat will have about the same capacity under a seated bullet as does the 470 Capstick. Anyone have performance data for that round?

Thanks.

Bwana-be - I ran you dimensions through the software and could not achieve 129gr.

The load data is for reference only. You must start at least 10% lower and work your way up 1 grain at a time!

I modeled the case as follows:
Base OD - .582"
Shoulder OD - .565"
Shoulder angle - 35 degrees
Neck length - 0.475"
Case length - 2.57"
Cartridge overall length - 3.34"
Estimated case capacity - 119.5 gr
Useful case capacity with 1.27" bullet ~ 97 gr

Optimum load (100% density) - 96.5 gr
Chamber pressure - 50,000 psi
Bullet weight - 500 gr
Muzzle velocity - 2350 fps

Best powders would be H335, W748, & 4895. H380 is on the slow side, but suitable with light/moderate compression. H414 is too slow for optimum performance.

Information on the 470 Capstick.

Case capacity ~ 112.5 gr
Useful case capacity (same bullet as above) 91.5gr
Loads are between 84 - 92 gr of powder
Chamber pressures are between 57000 - 62000 psi
Muzzle velocity (500gr bullet) 2350 - 2420 fps

The 470 Capstick will like faster powders than your wildcat.

Have fun, but be safe.

You know why they call it 'Quickload'? Because it will always predict a load which is quicker than reality! The pressures will always be low too.

[ 10-30-2003, 05:11: Message edited by: Judy ]

aww, and it PROMISED to not post in here..

troll warning

. i think your village misses you
jeffe

[ 10-30-2003, 05:52: Message edited by: jeffeosso ]

Jeffe, that only took you about 30 minutes. You're getting faster.
Judy, try it with a .587" base, and .575" shoulder, if you don't mind. In RCBS.load on a Lapua Mag case that gives about 106g under the bullet. May be a difference between Lapua and Rigby, but I thought the Rigby held more, b/c of thinner web.
No matter, really, I think this thing is going ot roar. It's easy to get caught up in the bigger-and-better thing, especially with big bores (for me), but smaller rounds have killed bigger animals than this one and I ever will.
And anyway, I know I'm just gonna end up with a 470 Mbogo one of these days....

BB,
We shot mike's 470 mbogo 2 weeks ago... 500s at 2300... yeah, it's far short of the max, but he wanted a laod just a bit better than the 470 NE...

it's PLEASENT to shoot, at 11# with one merc tube in it. I put the tube in for him, and offered to weight it a bit more, but we decided, after fitting the stock to him, that we'ld try first.

SO, 11#, merc tube, 470/500gr at 2300 feels NICE

jeffe

WOW!!

Imagine that..

two different software tools gave just about perdactly the same results

Judy's "unknown" software
Optimum load (100% density) - 96.5 gr
Chamber pressure - 50,000 psi
Bullet weight - 500 gr
Muzzle velocity - 2350 fps

jeffe's quickload
50000 psi gr %
Hodgdon H414 96.6 102.7 2333

Seems that quickload and Judy's "unknown" work just about the same...

jeffe

Bwana-be - Rerunning the case volume calculation using your new base diameter of 0.587" and shoulder diameter of 0.575" estimates the following:

Case volume - 122.4 gr
Useful case volume with your bullet - 100 gr
Load Density of 100%
Chamber pressure of 50,000 psi
Muzzle velocity of 2340 fps

Increasing the load to 106%
Chamber pressure to 57,500 psi
Muzzle velocity of 2462 fps

Rereading your orginal post I see that your simulation yielded a 2400 fps muzzle velocity at 44,600 CUP. My simulation shows a chamber pressure of ~ 53,800 psi for a muzzle velocity of 2400 fps. I would not be surprised at all to find that 44,600 CUP is equivalent to 53,800 psi for this cartridge. I guess, I am saying that, your orginal analysis may not have been too far off pressure wise.

You won't be able to obtain a case capacity of 129 gr. For your information, the 416 Rigby case capacity, measured not calculated, is:
Federal - 126.7 gr on average
Norma - 127.4 gr on average

My software's calculated case capacity is 127 gr for the 416 Rigby. All in all, a very good correlation.

The 495 A Square has a case capacity of 132.5 gr. It is a straight walled .510 caliber case with a 2.8" length. It is made from necked up and slightly shortened 460 Weatherby magnum cases. My ex-husband once built one, and I have considerable reloading notes for it.

jeffeosso dear, the problem is that my software is accurate, and your's is, well, wrong! You will NOT get, that muzzle velocity, out of this case, with H414! If your Quickload H414 load was actually tested in a 24" barreled rifle chambered for this cartridge, the muzzle velocity would be ~ 2180 fps. You might even have some unburned powder in the bore.

You see jeffeosso dear, it is all about volumetric expansion ratio. H414 is too SLOW of a powder for this case. It will go BOOM alright, it just won't provide the optimum muzzle velocity.

Ah, Judy... honey baby love...

quote:

---

Originally posted by Judy:
Hubel you and I both know jeffeosso is beating a DEAD horse. I am done with this thread. As a matter of fact I am done posting with you guys. I think I will just remain on the political forum.

---

jeffe

Sorry about the troll bashing...

there's this very viseral saying, in tex-mex spanish, that translates closely to
hizo mi da�o del pene

a pain in a sensitive place

[ 10-31-2003, 06:28: Message edited by: jeffeosso ]

jeffeosso - do you know why your 'example' with the 30-06 works so well for the H414 powder? I do, and I KNOW you do not!

BTW, the 475 Lapua magnum we are discussing on this thread AIN'T A 30-06!

Can you explain to us ALL what 'volumetric expansion ratio' is?

Assuming you can find the answer to question above, that would be the one dealing with what volumetric expansion ratio is, answer this question big boy. How does a powder's burn rate correspond to the cartridge's volumetric expansion ratio?

When and IF you ever find the answers to these questions I will be happy knowing that I have educated yet another ignorant man!

EDIT

Have you found a 50 caliber cartridge yet which will fit in a Marlin lever action rifle, which will out perform a 500 NE 3" when the maximum average pressure is maintained below 41,000 psi? NOT YET! How very surprising! I mean I am in SHOCK & AWE!! Oh yes, please no more BULLSHIT about using a 495 A Square. I have shot one you know. It won't fit in any Marlin lever gun, no way, no how!

Final question, jeffeosso dear, how did I pick a fight?

[ 10-31-2003, 06:34: Message edited by: Judy ]

jeffeosso - that is what I thought. Please consider this our last conversation. . . PERIOD ! I will ignore anymore of your ranting and whining.

I apologize to the rest here for wasting your time 'communicating' with this JERK .

EDITED - for obvious reasons. This JERK just makes me SSsssooooo mad!

[ 10-31-2003, 15:51: Message edited by: Judy ]

Damn Judy, it sounds like jeffeosso has given you a case of the pussy wiggles. Sounds like you want him bad.

No crowrifle, it is just one of my personal idiosyncrasies! I just cannot stand ignorance and bullshit! jeffeosso possess both in SPADES ! But I took a tranquilizer and can deal with his diatribes & BS better now.

Besides all that, I have out grown my manhunting stage of development. Been there done that! I prefer the company of myself and my children, now. Men are just too damned immature & childish to deal/live with!! They will lead any honest woman to an early grave!

[ 10-31-2003, 17:42: Message edited by: Judy ]

Yep, you got it bad for him.

Relax.

Give in.

Just let it happen.