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Old October 31, 2010, 12:23 PM   #1
psychobily
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Figure'n pressures

OK, here's the deal. I have a .257 STW and I have data for nosler bullets and RL-25 but I would like to try the Berger VLD 110 gr bullets. Does anyone here know how to figure out a good safe start load???

I looked at my nosler data and it says around 82grs MAX with RL-25.... I loaded up some already but I would like some feed back on if anyone knows how to figure safe pressures. I seen someone respond here a while back about pressures so I know someone here has the knowledge.

I am use'n Federal 210 primers as the guy that built my rifle said he has noticed primers pierced when use'n GM215s...


and my plan is to shoot until I see pressure signs on the brass... If there is someone here and does know how to figure pressures would you please PM me if you need more info. I would rather keep this in PMs until something is proven.

thanks in advance
PB
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Old October 31, 2010, 12:31 PM   #2
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Generally, you reduce the MAX load by 10% and use that as a start load.

With small capacity rifle cartridges a 15% reduction is sometimes a good starting load.
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Old October 31, 2010, 12:49 PM   #3
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OK, well the .257 STW I wouldn't really call a "small capacity" cartridge. I mean it's a 8mm Rem Mag cartridge necked down to .257cal.

I called Berger and there is no reload data at all on this cartridge so 10% of what is kinda my question. Since it is a Wild Cat cartridge Walt Berger wouldn't even touch it and that's understandable. That's why I need someone who knows how to work pressures up so I can figure out that "10%" you recommended.

Thanks shoney
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Old October 31, 2010, 12:54 PM   #4
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If you have load data for Nosler bullets, a 90% starting load for a Nosler would be OK for a Berger of about the same weight.

Pressure signs on the brass. Wow.
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Old October 31, 2010, 01:12 PM   #5
wncchester
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"...if anyone knows how to figure safe pressures."

Chamber pressure is measured or observed when it gets out of hand. But it ain't figgered.

There is a computer program (Quick Load) that projects pressures, etc. It works real well IF your rig is exactly like the one the programmers modeled their wild-ass guesses on. Otherwise....??
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Old October 31, 2010, 01:27 PM   #6
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Quote:
Originally Posted by wnnchester
It works real well IF your rig is exactly like the one the programmers modeled their wild-ass guesses on. Otherwise....??

That is a misrepresentation of QuickLoad. The entire program is adjustable to match the exact parameters of your particular gun, powder, case, bullet and environmental conditions.

You are not stuck with "the programmers modeled... wild-ass guesses..."



To the OP:

Just so you know, with default settings, QuickLoad predicts 82.0gr would be well over max pressure with the 110gr Bergers.

Max pressure is predicted at 78gr, starting load would be 90% or 70.2gr

In all likelihood, true max is slightly higher because QuickLoad defaults for case capacity are typically quite conservative but you'd need to provide the exact data in order to get a better prediction.
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Last edited by Brian Pfleuger; October 31, 2010 at 01:39 PM.
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Old October 31, 2010, 02:36 PM   #7
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When you have a very large cartridge case with a very small bore,things go very wrong suddenly.They are not forgiving.
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Old October 31, 2010, 05:24 PM   #8
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"You are not stuck with "the programmers modeled... wild-ass guesses..."

Yeah. Sure. Sorry. My mistake. ??

So, you can readily adjust Quick Load for your specific chamber, case wall thickness, bullet hardness, bullet contact surface, bore/rifling roughness and diameter, powder lot and primer lot variations, etc. or....maybe not. ?

I know something about computer modeling. I worked with programmers, engineers and scientists for a loong time and I'm not totally impressed with them or their projections. (Nor is anyone else who has followed the "scientific consensus on global warming" farce.) When the program matches the relivant data, the programs work fairly well. Otherwise, not so much.
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Old October 31, 2010, 06:16 PM   #9
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Let's not get into a P'ing contest about QuickLOAD

The program has been around long enough that it is a known quantity. Let's use it to address the OP's question.

If the OP measures his FIRED case capacity, bullet length, and loaded over-all cartridge length, then QuickLOAD can do a decent job of predicting a safe starting load. If the OP provides chronograph measurements for the velocities of the starting loads, then QuickLOAD can be tuned to give pretty good projections of pressure and velocity for his gun.

While it is not pressure-tested data, it is about the best thing you can do with a wildcat cartridge short of buying pressure-testing equipment.

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Old October 31, 2010, 08:26 PM   #10
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Using Standard primers to light 75-80gr of RL-25, or any slow burning powder is not advisable. As stated, the 257 STW is an extreme over bore (case volume/bore size) cartridge.
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Old November 1, 2010, 06:05 AM   #11
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Quote:
If the OP measures his FIRED case capacity, reply~ how do I measure the case capacity? bullet lengthreply~ berger VLD, 110 grain hunting bullets 1.196", and loaded over-all cartridge length,reply ~ 3.610" then QuickLOAD can do a decent job of predicting a safe starting load. If the OP provides chronograph measurements for the velocities of the starting loads, then QuickLOAD can be tuned to give pretty good projections of pressure and velocity for his gun.
Alls I need to know is how to measure the "FIRED" cartridge. I think I saw something on here before about filling it with wader and then measure'n the wader????? Let me know.
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Old November 1, 2010, 06:50 AM   #12
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To measure the case capacity, use a fired case that has not yet been resized. Leave the primer in the case. Weigh the empty case. Then fill the case with water and weigh it again. The difference in weight is the capacity of the case in grains of water.

Two details are important. One is the length of the actual case measured. Not all cases are the same length, so the actual length of the measured case CAN be important. In your situation with a way large capacity case and a small bullet diameter, this is not really significant. But it can be a substantial issue for small, straight walled pistol cases, so I want to include that in this thread that will be read by many other people.

The second detail is to make sure that the water level is flat across the case mouth. The easiest way to do that is to use an eye dropper to add water to the case, fill the case until the water level is bulging out of the mouth so that it completely wets the entire inside surface, the carefully suck enough water back out until the surface is flat. Looking at the reflection of something bright with a straight edge (like a window or flourescent light bulb) on the surface of the water in the case will help you see when the water surface is flat.

Also, it is important to make sure that you don't have bubbles inside the case. Holding the case mouth under the tap can leave bubbles in bottle-necked cases, but filling them with an eye dropper usually doesn't do that.

Case capacities can vary from brand-to-brand by as much as a few grains in large capacity cases like yours, so make sure that you are using cases with the same capacity when you are working-up this load.

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Old November 1, 2010, 07:01 AM   #13
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Thanks SL1! I'm going to the range today after my meeting and I will bring home a fire case and get back to you on the weights. Thank you so much for the information you have provided.
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Old November 2, 2010, 05:58 AM   #14
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.257 STW

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

I went to the range yesterdee and came up with some data. SL1 I also weighed the brass like you said you needed for your software.

Fired brass weight is 257.1 gr
Fired brass w/water is 355.8 gr
bullet length is 1.196"
berger VLD, 110 grain hunting bullets

I'm loading .050" off of the lands as well as I've been told "kissing the lands" can possibly cause higher pressures.



Bullet Berger VLD
Bullet Weight 110 grs
Powder Reloader 25
Powder WT (see below data)
Primer Fed GM210M (yes, large rifle NOT mag)
Brass Make Remington
Barrel Length 26 (inches)
C.O.L 3.609 (inches)
Velocity (see data below) fps
Group 100 yds (see data below) (inches)
Gun Info .257 STW Custom Rem 700 1 in 9" twist shilen
Comment This is data I've worked up to ***CAUTION***


1st round 77.5 gr ~ 3470; 3501; 3508fps
2nd round 78.0gr ~ 3560; 3565; 3565fps (3/4" group)
3rd round 78.5gr ~ 3569; 3560; 3567fps
4th round 79.5gr ~ 3654; 3654; 3650fps
5th round 79.8gr ~ 0000; 3670; 3670fps
6th round 80.2gr ~ 3688; 3632; 3669fps (5/8" group)

I'm close with that 80.2gr but I want to go up a couple of tenths and down to try and bring it in tighter. SL1 I would like to know what your software says for MAX. The brass didn't show any signs of over pressure that I could see.... It sure is a sweet shooter.
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Old November 2, 2010, 10:16 AM   #15
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Quote:
Originally Posted by psychobily
I'm close with that 80.2gr but I want to go up a couple of tenths and down to try and bring it in tighter. SL1 I would like to know what your software says for MAX. The brass didn't show any signs of over pressure that I could see.... It sure is a sweet shooter.
With your indicated variables and the QuickLoad "weighting factor" adjusted to indicate the rather substantial "over-bore" status of the 257 STW, it predicts 60,416 psi at 80.2gr, with a muzzle velocity of 3629fps.

That prediction is 99.07% of your indicated velocity, .93% error.
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Last edited by Brian Pfleuger; November 2, 2010 at 10:24 AM.
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Old November 2, 2010, 03:47 PM   #16
psychobily
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lol too funny! It sounds like that quick load is some cotten pick'n good software...

Do you think I can go a couple of tenths of a grain higher, safely? I don't know a lot about pressures so I don't know what the action can handle... I'm gunna drop it down a couple tenths to fine tune it but I may need to go up.... I may even want to bring it closer to the lands as well but I reckon that will increase the pressure too????
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Old November 2, 2010, 05:56 PM   #17
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Old November 5, 2010, 10:18 AM   #18
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QuickLoad & pistol rounds?

a slight hi-jack, will QuickLoad work with handgun rounds (straight wall cases), any powder,any bullet weight, and any cartridge chambering ? Thanks
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Old November 5, 2010, 08:20 PM   #19
Jim Watson
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There was a thread about that here a few months ago.
My RECOLLECTION is that QL is not as predictive for straight wall cases as bottleneck. The users gave some tweaks which seemed to amount to a circular process; if you fudged the starting point until you got a known result for a known load, you would get usable estimates for loads not too different.
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Old November 6, 2010, 10:06 AM   #20
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Thanks, I'll do a search on QL here or maybe give them a call and get it straight from them.
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Old November 6, 2010, 11:27 AM   #21
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QuickLoad is somewhat less accurate with straight wall cases, particularly small capacity pistol cases.

It seems to depend a lot on the particular cartridge/powder/bullet combo because sometimes the numbers are very good, and sometimes they're not.

QuickLoad predicted the velocity of 180gr Hornady XTPs with Power Pistol in my uncles 10mm to a very good accuracy level.

I have helped a few guys with data for 9mm using various bullets and sometimes the data seems good, sometimes not so good.

On the other hand, much the same can be said about the data for bottleneck rifle cartridges. QuickLoad is almost dead on for every load I've tried in 204Ruger, 22-250 and 7mm-08 but it strangely predicts a max load that is actually WAY OVER max using IMR 3031 and Barnes TTSX bullets in the 7-08.

Bottom line, QuickLoad is a predictor and indicator, not a replacement for knowledge, work and common sense.
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Old November 6, 2010, 08:06 PM   #22
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"Let's not get into a P'ing contest about QuickLOAD"

Not me, I've given all I have to say about such programs. Everybody gets to play with anything he wishes and do it with my best wishes and cordial blessings!
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Old November 8, 2010, 08:58 AM   #23
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My wife and my son are software engineers, and when they operate my computer all kinds of fancy things are happening.
I wish someone who is good at Quickload would come over to my house and show me some new tricks.
All I know is that if I get Quickload to match the velocity of the chronograph, then the threshold of short brass life with look like:

1) The 1889 Mauser 7.65x53mm case head design, when built with a large Boxer primer
Examples: 22-250, 243, 6mm Rem, 250 Savage, 257 Roberts, 25-06, 260 Rem, 6.5x55 [US brass], 270, 7mm-08, 7x57mm, 280, 300Sav, 308, 7.62x51mm, 30-06, 8x57mm, 338F, 358, and 35W.

Rifles I have; 22-250, 243, 250 Savage, 260 Rem, 6.5x55 [US brass], 270, 7x57mm, 300Sav, 308, 7.62x51mm, 30-06, 8x57mm, and 35W.

Quickload predictions of 70kpsi are the threshold of short brass life.
Quickload predictions of 75kpsi are loose primer pocket in one shot with new brass.

2) The 1950 designed .222 case head with small rifle primer
Examples: 17 Rem, 204 Ruger, 221 Rem Fireball, .222 Rem, .223 Rem, 5.56x45mm, .222 Rem mag, 6x45mm.

Rifles I have; 223 Remington

Quickload predictions of 80kpsi are the threshold of short brass life.
Quickload predictions of 85kpsi are loose primer pocket in one shot with new brass.

3) The 1889 Mauser 7.65x53mm case head design, when built with a small Boxer primer
Examples: 22BR, 6mmBR, 6x47mm, 6.5x47mm, 7mmBR, 30BR, Lapua small primer 308

Rifles I have: 6mmBR [243, 260, and 308 testing forthcoming]

Quickload predictions of pressure do not correspond to brass life, but to primer piercing, which is a function of the firing pin and the primer used. CCI small rifle mag is best.

4) The 1925 Holland and Holland 300 H&H Magnum built with large Boxer primer
Examples; 6.5mm RemMag, 7mm RemMag, 8mmRemMag, 264 WinMag, 300 H&H Mag, 300 WinMag, 338 WinMag, 350 RemMag, 375 H&H Mag, 458 WinMag

Rifles I have; 7mmRemMag, 300WinMag, 338WinMag

Quickload predictions of 75kpsi are the threshold of short brass life.
Quickload predictions of 80kpsi are loose primer pocket in one shot with new brass.
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Old November 8, 2010, 09:21 AM   #24
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There is an engineer out there that can calculate brass stress.

The part that corresponds to 257STW is:

Quote:
22 June 2004 07:43
Clark,
Here are the results of the von Mises stress calculations ..
Using mechanical properties for C26000 brass (cartridge brass)
Temper - H06
Tensile yield strength - 65,300 psi
...
The H&H magnum case head nominal condition chamber pressure for the initiation of case head yielding with H06 C26000 brass is: 79,597 psi


Scott Sweet
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Old November 9, 2010, 07:17 AM   #25
psychobily
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That sounds spot on to what a top bullet mfg wrote back to me say'n. Well he stated that the max cartridge pressure was 63817psi, so that's close.....
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