Quickload confusion

[TNVolunteer]

I have a question concerning "Maximum Case Capacity, overflow" and "Case Length".

The manual states

It is imperative to accurately determine the average capacity for a given group of cases (brand
and lot) because case capacity differs substantially from lot-to-lot and brand-to-brand. This
measurement is easily done using a dry, empty fired case (with fired primer in place).
(For published loading data anywhere in magazines we often find case brand information
together with bullet, charge and primer data. This is tradition, but it makes no sense at all.
Cases are often "outsourced" manufactured, so in truth the manufacturer of one brand may
differ, and therefore the tools for drawing cases too).
For most RIFLE CALIBERS and other guns using peak pressures above 30,000 psi (2,000
bars): use a case fired in the specific gun you are working with. Do not resize the case before
making the capacity measurement.

In the section where the cartridge data is defined, the manual states

For high-pressure cartridges, use dimensions from a fired case.
Selecting Calculate button calculates case capacity (grains of water), based upon data
entries.

In the actual interface, the context bubble states

Water capacity of a typical case of the chosen type when trimmed to the specified length.
For high-pressure loads, measure after firing in a typical chamber (case not resized).

From all of the references, it is clear that a fired non-resized case is to be used. What is not clear to me is the trimming aspect.

My fired cases are typically .002-.004" undersized, so I would not want to trim them before FL sizing, so I would need to leave the case as is.

I assume the "specified length" refers to "Case Length".

In the interface, the description states

Length of empty (trimmed) case.
Distance from case mouth to case head. Default value is the length of a sample used for measuring case capacity.

The question for me is what to put here. The text clarifies that I should be using the length of the case used to determine "Maximum Case Capacity, overflow".


Based on plugging in some data, it doesn't appear to make much difference up to .010" on the "Case Length" value varying from the length of the weighed brass.

Fired Brass Length	H2O Capacity	Resized Case Length	Charge Grains	Velocity fps	Energy ft-lbs	Max Chamber Pressure psi	Muzzle psi	Propellant Burnt	Muzzle Velocity
1.900​	52.180​	1.900​	41.0​	2757​	2363​	61357​	9030​	99.9​	2757​
1.900​	52.180​	1.905​	41.0​	2759​	2366​	61544​	9027​	99.9​	2759​
1.900​	52.180​	1.910​	41.0​	2761​	2369​	61733​	9023​	99.9​	2761​

Writing this post made me think through this process and maybe answer my question, so I guess my ask is whether the approach below is safe and accurate.

1. For "Maximum Case Capacity, overflow", use a fired case and a primer pocket plug from 21st Century in place of the primer, weigh the case and plug empty and then with distilled water and subtract the difference.
2. For "Case Length", enter the length of the case from above.

Thanks for any feedback.

James

 

[Jager]

Yes, you seem to have come back around to the correct conclusion, after a long walk around the barn.

Case length is whatever it is. Whether you've trimmed it or not.

Maximum Case Capacity, overflow is however much water it holds, with a flat meniscus at the very edge of the neck. Using the 21st Century plugs instead of just leaving the spent primer in is fine.

QuickLoad will calculate case capacity based upon those two factors.

 

[Straightshooter1]

I have a question concerning "Maximum Case Capacity, overflow" and "Case Length".

The manual states

In the section where the cartridge data is defined, the manual states


In the actual interface, the context bubble states

From all of the references, it is clear that a fired non-resized case is to be used. What is not clear to me is the trimming aspect.

My fired cases are typically .002-.004" undersized, so I would not want to trim them before FL sizing, so I would need to leave the case as is.

I assume the "specified length" refers to "Case Length".

In the interface, the description states

The question for me is what to put here. The text clarifies that I should be using the length of the case used to determine "Maximum Case Capacity, overflow".


Based on plugging in some data, it doesn't appear to make much difference up to .010" on the "Case Length" value varying from the length of the weighed brass.

Fired Brass Length	H2O Capacity	Resized Case Length	Charge Grains	Velocity fps	Energy ft-lbs	Max Chamber Pressure psi	Muzzle psi	Propellant Burnt	Muzzle Velocity
1.900​	52.180​	1.900​	41.0​	2757​	2363​	61357​	9030​	99.9​	2757​
1.900​	52.180​	1.905​	41.0​	2759​	2366​	61544​	9027​	99.9​	2759​
1.900​	52.180​	1.910​	41.0​	2761​	2369​	61733​	9023​	99.9​	2761​

Writing this post made me think through this process and maybe answer my question, so I guess my ask is whether the approach below is safe and accurate.

1. For "Maximum Case Capacity, overflow", use a fired case and a primer pocket plug from 21st Century in place of the primer, weigh the case and plug empty and then with distilled water and subtract the difference.
2. For "Case Length", enter the length of the case from above.

Thanks for any feedback.

James

For load development, I don't use case measurements in QL until after I've got my cases fire formed. Usually by that time, case lengths are uniform after trimming and with uniform case lengths, I then will measure for the H2O case volumes.

If the case lengths are not the same, the measured case volumes won't be the same (given enough difference in case lengths). .010" difference in case length will result in a difference in measured volume (a lot depending on the caliber one is talking about).

Since I use an electronic scale, I don't do any math by just zeroing the scale and then fill to the rim to see what the weight come to be.

 

[Ned Ludd]

For determining case [water] volume, I use the following procedure:

Case Volume Determination (pic heavy)

Readers here will see many, many posts regarding determination of case volume. There seem to be about as many different methods as there are posts on the topic, such as using detergent or alcohol mixed with the water, how the primer pockets are sealed, how "full" the case should be filled...

forum.accurateshooter.com

I typically do this procedure with 10 fired cases selected randomly and use the average value, which means the outputs from QL will be pretty good for a given Lot# of brass, but perhaps not exactly perfect for any of them. It seems to work just fine. Remember, the QL outputs are predictions, not written in stone. I want to use the best inputs possible to get back the best predictions of which the program is capable of producing, but there are numerous caveats involved in the use of a program such as QL, and so I appreciate the fact that the outputs I am getting back from QL are necessarily approximations, not exact predictions that can completely account for every single variable involved.

In terms of case length, I use the intended case trim length; i.e. whatever case length I intended when I set the trimmer. If I actually measure the trimmed length of cases, they will typically be within +/- .001" or so of the intended length, but will have a range of lengths as most trimmers/settings don't perfectly trim every single case to exactly the same length within <.001". As @straightshooter 1 noted, minor case length variance will be covered when the water volume is actually determined with each case. That is part of the reason why I use the average of at least 10 case volume determinations.

As with any predictive program of this type, it is not difficult to get started simply by using the best data available. If over time one sees a better way to measure/input certain required data, their use of the program can easily be modified/refined as they learn more about it. After a while, most will realize the QL outputs are highly useful as general predictive information for the reloading process, rather than highly specific information for individual cases or loaded rounds. I would not get too far down into the weeds initially, as I don't think the program is capable of generating outputs that are meaningful at that level. Nonetheless, it is always a good idea when you encounter an input field such as case length that may be a little nebulous to compare a few values, perhaps using those at either end of the measured range, then compare the outputs to see how much effect subtle changes in a single input have on the outputs. That way, one can develop a good feel for how much effect each different input variable has on the outputs. For example, one can input a reasonable range of case lengths, holding all other inputs constant, and see what effect case length has on the outputs.

Edited to add: if you don't have the little rubber primer sealers, you can always just leave the spent primer in the case, or if you're extremely OCD like I am, you can decap the cases you intend to use for volume determination, turn the primers around backwards and re-insert them into the cases. This approach works pretty well for relatively small numbers of cases.

 

[mikecr]

I wouldn't try to calculate H20 capacity with QL.

I have been successful in predicting H20 capacity with 'Cartridge Designer' feature of RCBS DOT LOAD:

RCBS CD-ROM Dot LOAD Ballistics Software Version 3.4

Version 3.4 CD-ROM for Windows 95, 98, NT, 2000 and Windows 7. Features detailed schematics for over 517 cartridges. Bullet trajectories can be...

www.midwayusa.com

It's just better than QuickLoad or Quick Design for this.

Cases are dynamic, they spring back differently all over the place.
So ultimately, H20 capacity needs to be measured with initially annealed cases, fully fire formed to stable, then sized per your plan, and trimmed/chamfered. With that you'll be able to see the dynamic differences and cull out the witches.
You can get an average capacity there to tweak QL's default.

 

[jepp2]

I typically do this procedure with 10 fired cases selected randomly and use the average value, which means the outputs from QL will be pretty good for a given Lot# of brass, but perhaps not exactly perfect for any of them. It seems to work just fine. Remember, the QL outputs are predictions, not written in stone. I want to use the best inputs possible to get back the best predictions of which the program is capable of producing, but there are numerous caveats involved in the use of a program such as QL, and so I appreciate the fact that the outputs I am getting back from QL are necessarily approximations, not exact predictions that can completely account for every single variable involved.

@Ned Ludd is MUCH more disciplined than I am concerning case volume. I just grab 2 cases from the same lot (I already know the weight range of cases in the lot) and check them. They are almost always within 0.1 gr WC. Good enough for me.

As with any predictive program of this type, it is not difficult to get started simply by using the best data available. If over time one sees a better way to measure/input certain required data, their use of the program can easily be modified/refined as they learn more about it. After a while, most will realize the QL outputs are highly useful as general predictive information for the reloading process, rather than highly specific information for individual cases or loaded rounds. I would not get too far down into the weeds initially, as I don't think the program is capable of generating outputs that are meaningful at that level. Nonetheless, it is always a good idea when you encounter an input field such as case length that may be a little nebulous to compare a few values, perhaps using those at either end of the measured range, then compare the outputs to see how much effect subtle changes in a single input have on the outputs. That way, one can develop a good feel for how much effect each different input variable has on the outputs. For example, one can input a reasonable range of case lengths, holding all other inputs constant, and see what effect case length has on the outputs.

Predictive is the key word. What I find benefits my calculations the most is the Ba values (powder burn rate for the lot I am using) I found using this powder in loads I have already shot. I feel more than 75% of the accuracy of my predictions come from this. So spending a lot of time obsessing over other inputs yield much lower results for me.

I love QL and have used it for probably 15+ years for every load development I have done. But I started playing with GRT some recently, and once I learned the program I haven't used QL since. It has many outputs that QL doesn't offer. And it is free.

 

[Zero333]

300 WinMag is NOTORIOUS for having a big difference in case capacity from different brass makes.

I have 3 different brands of 300winmag brass I measured the H2O...

F.C. ( from FGMM fired in this one rifle) measures 92.5 gr H20 when fired and closer to 90.0 H20 when sized.
Winchester is closer to 94.1 gr of H2O when fired and 93.7 when sized.
Norma has the biggest boiler room at 95+ gr H2O when sized.

I have Hornady and Rem. 300winmag brass as well, but I don't use them. The Remington brass has off-center flash holes which many look more oval than round and the Hornady brass gave me pressure signs with starting loads.

 

[mikecr]

There will always be differences between brass brands, and lots in-brand.
But even if everything is the same,, brand, lot, sizing, even initial case capacity, each case has it's character.
So if you get your cases matching, and your reloading right, you can still have a case throw a shot.
Trash that case immediately.
Don't try to save it, or figure anything out. You've already done all you can. Just toss it and go on.

 

[Dimner]

I think you got it right. Not sure if someone else mentioned it already, but I just seat a used primer in the case that I'm measuring h2o capacity.

Also, even within the same headstamp of brass, there can be some variations on the H2O capacity. I tend to use 4-6 once fired cases. I'll deprime, tumble to clean them up, seat used primers, lable them and then measure each for H2O capacity. Then take the average of all of them as the value I use in QL.