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  #51  
Old 04-30-2012, 10:01 AM
Alland Alland is offline
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Quote:
Originally Posted by RetiredRod View Post
P1 x V1 = P2 x V2

or, restated, P2 = P1 x V1/V2 (the pressure is proportional to the ratio of the volumes)

That's the theory. In practice, it's almost impossible for a hobbyist to get a meaningful answer. First, you'd have to know exactly which bullet you're dealing with, and it would have to be a bullet well dimensioned in the manual, so that you'd know EXACTLY how far into the case the base of the bullet was seated to yield the pressure shown in the manual. If you can reliably establish that, then re-calculate the reduced case volume with the bullet seated deeper (i.e. .003" in the example above). With this new (smaller) case volume, use the volumetric ratio shown above to calculate the reduced case volume internal pressure.
The volume is only part of the answer. Modern smokeless powders are progressive burning. That is as the pressure increases the burning rate increases. The end result is the pressure rise is an exponential function of the volume not linear as this equation provides.

The rate of pressure rise due to decreased volume will vary with different powders. Quick Load, the internal ballistics program takes into account powder type and internal internal volume as well as many other variables to predict peak pressure and muzzle velocity.
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  #52  
Old 04-30-2012, 10:17 AM
ChrisG164 ChrisG164 is offline
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I would assume that regardless of the powder that burn rate is going to vary based simply on the available surface volume of the powder from the beginning of the burn throughout then add in the speed of the burn itself if it were linear, and i'm not even sure if the reduction in oxygen througout the burn itself is a variable? I guess this is why they have computer programs for this sort of thing.
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  #53  
Old 04-30-2012, 10:29 AM
Alland Alland is offline
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The available oxygen is not a factor, the powder contains it's own oxidizer.

I do not own Quick Load, but I have used it.

Some of the variables:

powder type
bullet weight
case volume
seating depth
distance the bullet moves before contacting rifling
internal pressure at the time bullet first moves (varies with how tight the bullet is in the case)

Needles to say that it cannot be reduced to a few calculator functions.
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  #54  
Old 04-30-2012, 11:19 AM
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Quote:
Originally Posted by ChrisG164 View Post
BUT, on the other hand. What is .03 really going to cause if the bullet is seated that much deeper? I'm still not up on any of the algorythms to calculate pressures.. but I'd like to know what kind of pressure increase that is going to cause approximately, for a 9mm `120 grain LRN bullet and cartridge..?

You can't 'calculate' pressures. You have to use pressure testing equipment, and take actual measurements.

But, you can trust us when we say a .030 increase in seating depth in a full power 9mm load is going to send pressure through the roof. Depending on the gun to set it off in, it may or may not blow a case. That is NOT an experience you want to have.

Don't fool around with this stuff, listen to what we're telling you.
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  #55  
Old 04-30-2012, 12:41 PM
ChrisG164 ChrisG164 is offline
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Quote:
Originally Posted by Rifter View Post
You can't 'calculate' pressures. You have to use pressure testing equipment, and take actual measurements.

But, you can trust us when we say a .030 increase in seating depth in a full power 9mm load is going to send pressure through the roof. Depending on the gun to set it off in, it may or may not blow a case. That is NOT an experience you want to have.

Don't fool around with this stuff, listen to what we're telling you.
Why would I start with full power load for the first time with a bullet I haven't used before
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  #56  
Old 04-30-2012, 01:13 PM
Alland Alland is offline
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Quote:
Originally Posted by ChrisG164 View Post
Why would I start with full power load for the first time with a bullet I haven't used before
I would hope you wouldn't, but seat a bullet too deep even with a starting load can very well take you over maximum pressure. Maybee not blow out a case pressure but certainly over maximum is possible.
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  #57  
Old 04-30-2012, 01:53 PM
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Quote:
Originally Posted by ChrisG164 View Post
Why would I start with full power load for the first time with a bullet I haven't used before
The amount of powder space is small enough in a 9mm that there isn't that much difference between a starting load and a full load. There's a fine line with certain powders where as little as .5 gr. is all the leeway you have. In any case, full power doesn't necessarily mean red lined pressure wise. A standard velocity factory 115 gr. is a full power load, but push that bullet another .030 into the case and you've turned it into a miniature grenade (at least potentially).
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  #58  
Old 04-30-2012, 06:22 PM
CHESAPEAKE CHESAPEAKE is offline
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Wow

Quote:
Originally Posted by ChrisG164 View Post
Why would I start with full power load for the first time with a bullet I haven't used before
Chris -

Here's a couple of suggestions :

A.} Buy yourself a 1 Lb. Container of W- 231

B.} Research the Load Data from Winchester

C.} Work your way up starting at MINIMUM LOAD

D.} Diligently check your loads for correct O.A.L Overall Length Of Cartridge

THE most knowledgable folks on this forum have tried to help you, and for whatever reason , ..................... well, you know.

Use the AUTO-COMP Powder when you gain more " Real Time " experience -
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  #59  
Old 04-30-2012, 06:56 PM
TheGerk TheGerk is offline
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Quote:
Pretty good idea on that guys part. Not to go on a tangent but I've been having issues with the bullet puller. That is, I've had to hit pretty hard and about a dozen times to get some bullets out. I'm thinking I may be seating the bullet too deeply or crimping too hard maybe. Either way, it's a cause for lower velocity/higher pressure and higher chance of a squib. I haven't measured the neck of the bullet seating depth but it's just over 2/8" not excessive.
Quote:
just measured 3 different bullets. One copper coated RN, one LRN and one LSWC. non of them deviating more than 3/100's from one another. I fail to see the danger in this instance..?
Quote:
BUT, on the other hand. What is .03 really going to cause if the bullet is seated that much deeper? I'm still not up on any of the algorythms to calculate pressures.. but I'd like to know what kind of pressure increase that is going to cause approximately, for a 9mm `120 grain LRN bullet and cartridge..?
In several of your post you keep making these numerical expressions that are in error.
In Handloading, we measure and express lengths and diameters in Thousandths of an Inch (0.000 or .000)

Not eighths of an Inch 2/8" or Hundredths of an Inch 3/100's & .03

We are assuming you are making your critical measurements with a dial caliper, scaled in 0.000 (One Thousandths of an Inch) and hopefully of some dubious quality.

I can’t express how important it is to get this area of your Handloading “dialed” in.
Inconsistency in readings and values here are a recipe for disaster.
Not mastering this numerical discipline can also bleed over into other aspects of your loading including the safe operation of your scale or mismatching components due to measurement error, or the misinterpretation of these values.

In Handloading, it is usually the “smallest” thing that comes back to haunt you the most.

Good Luck
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  #60  
Old 04-30-2012, 07:58 PM
ChrisG164 ChrisG164 is offline
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Quote:
Originally Posted by CHESAPEAKE View Post
Chris -

Here's a couple of suggestions :

A.} Buy yourself a 1 Lb. Container of W- 231

B.} Research the Load Data from Winchester

C.} Work your way up starting at MINIMUM LOAD

D.} Diligently check your loads for correct O.A.L Overall Length Of Cartridge

THE most knowledgable folks on this forum have tried to help you, and for whatever reason , ..................... well, you know.

Use the AUTO-COMP Powder when you gain more " Real Time " experience -
Better safe than sorry, is the term? Just one question.. Why do you recommend that particular powder?



Quote:
Originally Posted by TheGerk View Post

We are assuming you are making your critical measurements with a dial caliper, scaled in 0.000 (One Thousandths of an Inch) and hopefully of some dubious quality.
Then you're assuming correctly. If I've made any nonchalant mention of a length in a form other than this it's merely to make a representation of what's in front of me.
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  #61  
Old 05-01-2012, 08:19 AM
rfd rfd is offline
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Quote:
Originally Posted by ChrisG164 View Post
... Just one question.. Why do you recommend that particular powder? (w231) ...
i already posted why you don't wanna use autocomp and why a powder such as w231 is better - for you, the newbie reloader ..........

1. there are way too few listed/proven autocomp loads for 9mm (or any other caliber).

2. the start/max load weight spread range for autocomp is 1/2 grain, while for w231 it's 1 full grain = safer loading due to a doubled safe powder loading range.

3. LOTS of data abounds everywhere for proven powders such as w231.
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  #62  
Old 05-01-2012, 08:45 AM
ChrisG164 ChrisG164 is offline
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Sorry.. Just remember how much info (as a newbie reloader) Is necessary to soak up when including ALL the info you and the board have provided me. I'll just say LOTS!

TY for the refresher.

BTW I just got my XD back from PRP for it's trigger job and sight swap. I'll be posting a thread with vid on that shortly. I also just posted a review on the Lee Adjustable Charge Bar in this forum area a couple minutes prior.
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  #63  
Old 05-01-2012, 12:34 PM
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Quote:
Originally Posted by ChrisG164 View Post
Sorry.. Just remember how much info (as a newbie reloader) Is necessary to soak up when including ALL the info you and the board have provided me. I'll just say LOTS!
Exactly, and that's why we're telling you to start with one powder and one bullet and making some recommendations of which ones to start with. That's so that you learn the ropes and live to be an OLD reloader and not a statistic missing an eye or a couple of fingers.
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  #64  
Old 05-01-2012, 12:57 PM
ChrisG164 ChrisG164 is offline
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Quote:
Originally Posted by Rifter View Post
Exactly, and that's why we're telling you to start with one powder and one bullet and making some recommendations of which ones to start with. That's so that you learn the ropes and live to be an OLD reloader and not a statistic missing an eye or a couple of fingers.
Well, I'm taking your advice and starting with the good 'ol Lead RN bullet.. only the plunk test is revealing that the cartridge stops about a couple hundredths of where it's supposed to be landing in the barrel before it comes to an abrupt stop.
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  #65  
Old 05-01-2012, 01:32 PM
rfd rfd is offline
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Originally Posted by ChrisG164 View Post
Well, I'm taking your advice and starting with the good 'ol Lead RN bullet.. only the plunk test is revealing that the cartridge stops about a couple hundredths of where it's supposed to be landing in the barrel before it comes to an abrupt stop.
issues for failing your 9mm barrel plunk test - taper crimp diameter too large, oal too long, case too long.
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  #66  
Old 05-01-2012, 02:34 PM
CHESAPEAKE CHESAPEAKE is offline
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Versatile

[QUOTE=ChrisG164;3846358]Better safe than sorry, is the term? Just one question.. Why do you recommend that particular powder?


WINCHESTER 231 is :

A.} Versatile for a number of different Cartridges.....................

B.} Meters well " on the drop ".

C.} Economical / Clean Burning / Consistant
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  #67  
Old 05-02-2012, 06:26 PM
ChrisG164 ChrisG164 is offline
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Quote:
Originally Posted by rfd View Post
issues for failing your 9mm barrel plunk test - taper crimp diameter too large, oal too long, case too long.

[QUOTE=CHESAPEAKE;3847812]
Quote:
Originally Posted by ChrisG164 View Post
Better safe than sorry, is the term? Just one question.. Why do you recommend that particular powder?


WINCHESTER 231 is :

A.} Versatile for a number of different Cartridges.....................

B.} Meters well " on the drop ".

C.} Economical / Clean Burning / Consistant

Thank you & Thank you
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