Case Capacity and grouping.

For practical purposes, your weight distribution is excellent.

Weight is not case capacity.

The variation in case weight is from variation in the cut of the rim between production runs.

There is a variation in volume between cases, it's always small, not exactly repeatable, and never directly related to case weight. By not repeatable, I mean if you measure the volume of a fired case, reload it, fire it, measure again, it won't have the same volume. That's why I never bother trying to sort cases by weight or volume.

You can ignore case volume differences if the brass is all one headstamp.

There is a material difference in case volume from one brand to the next, and that is due to the case wall thickness. PMP has the smallest case volume relative to others in most calibers, for example.

If you're confident there is nothing wrong with anything on the rifle, I suggest an OCW test. 15 rounds is all it takes to see which load is best for the bullet.

Did a case volume test in mean time, total volume spread is 0.6 grains H2O.

If you're confident there is nothing wrong with anything on the rifle, I suggest an OCW test. 15 rounds is all it takes to see which load is best for the bullet.

>>>>>>>>>>>>>>>>>>>>>>>>
I really need to try learn, understand this OCW test, never took much notice of it.

Just looked up this OCW, it stands for Obsessive Compulsive Worker. Gees, a day at the range, I love reloading yet hate being at the range, half my trouble is I rush the range time.

I guess it comes down to my main issue again - finding time and the willingness to sit and do it slowly (waste time), hate slowly, can not do things slowly.

Perhaps i must find a day to do this whole OCD thing :-

I have a strong belief in QL to get me close to an accuracy node. From there you can move up and down in small increments to refine the load. I have offered to help big5ifty but have not received figures to work with.

I got an excellent group with Kriek 48gr bullets in my 223. The figures below from a QL calc showed that I was close to a node. That is not a coincidence as I have tested and got good results in other calibres as well.

5 Mar 2021 Vliegveld Fed Match Sako Riflex RFL QL prediction for node
57mm Speer 55 25 3134 25,9 3255
57mm Hornady 55 25 3142 25,8 3244
56mm Kriek 48 25 3234 Skote sny amper 25,2 3266

I once measured 100+ PMP 308 cases, probably closer to 150 pieces. There was a correlation between case weight and case capacity, but it was small enough that my own shooting ability would have had a larger impact.

Your QL load work and understanding is phenomenal, I have found your helps to be within 20 -30 fps on occasion. I would rule out coincidence, total faith in your work to date.

I once measured 100+ PMP 308 cases, probably closer to 150 pieces. There was a correlation between case weight and case capacity, but it was small enough that my own shooting ability would have had a larger impact.

************************
I have just found that a rather large case weight difference delivered a rather small H2O capacity difference. nearly 5 gr weight dispersion in cases had a 0.7 gr case capacity difference.

The worst differences in case weight vs case capacity was with 303 cases.

I have offered to help big5ifty but have not received figures to work with.

Not because I don't trust your method. I intend to make use of your expertise when I do load development for the new bullets I have coming on order. The rifle is in for a bit of work, and the scope mount will change, so when ready, you'll hear from me.

I have just found that a rather large case weight difference delivered a rather small H2O capacity difference. nearly 5 gr weight dispersion in cases had a 0.7 gr case capacity difference.

0.7 grains is the weight of one drop of water.

Had a look on QL and with 223 (30,3 H2O) 1gr volume = 46fps speed difference. With 7x64 (66,9 H2O) it is only 23fps. It is a known fact that ES is larger with smaller calibres, but decent grouping is still achieved.

Had a look on QL and with 223 (30,3 H2O) 1gr volume = 46fps speed difference. With 7x64 (66,9 H2O) it is only 23fps. It is a known fact that ES is larger with smaller calibres, but decent grouping is still achieved.

In "The Houston Warehouse" article, the writer mentions that .22 calibre cartridges give the best accuracy?

I think that most of us still have much to learn.

In "The Houston Warehouse" article, the writer mentions that .22 calibre cartridges give the best accuracy?

I think that most of us still have much to learn.

I think that is due to the small powder charges providing reduced shock waves with which to vibrate the barrel.

It remains to be seen if structured barrels can invalidate that observation.

Please consider this: does the Houston Warehouse experiment count for regular shooting conditions? They had a large, windless area under unchanging light conditions?

Please consider this: does the Houston Warehouse experiment count for regular shooting conditions? They had a large, windless area under unchanging light conditions?

*********************
Yes of course, the stable conditions gave very accurate base line results. Its like saying a 3 inch group load is good enough for hunting and then telling a bloke that can only shoot a three inch on a good day with a half inch grouping capable rifle that a 3 inch group is good enough for hunting.
Now take the 3 inch capable rifle and let the 3 inch capable shooter shoot it and he will get anything from spot on the bulls eye to his max 3 inch off + the rifle does a 3 inch off on that shot = a 6 inch off shot. If both were o inch capable you would get a zero inch group, if only of the two was zero inch capable and the other 3 inch able you would get a 3 inch off shot.
The stable conditions only made fore more accurate knowledge of what can be achieved with a weapon and load, all added conditions are different tests.

Please consider this: does the Houston Warehouse experiment count for regular shooting conditions? They had a large, windless area under unchanging light conditions?

That whole exercise was absolutely fascinating to read about. I'm pretty sure that there were things found out in those conditions that would be all but impossible to have been found out any other way

Please consider this: does the Houston Warehouse experiment count for regular shooting conditions? They had a large, windless area under unchanging light conditions?

Not any regular condition, the perfect condition that completely removed wind from the result.

The one thing that stuck in my mind from that was best accuracy was achieved without handling the rifle at all, just touching the trigger.

Please consider this: does the Houston Warehouse experiment count for regular shooting conditions? They had a large, windless area under unchanging light conditions?

Not any regular condition, the perfect condition that completely removed wind from the result.

The one thing that stuck in my mind from that was best accuracy was achieved without handling the rifle at all, just touching the trigger.

******************************
I also hold that as my most notable take away, free rifle, just trigger contact.

He also mentioned that .22 calibre cartridges gave the best accuracy, and one of the very last lines he mentions he achieved something like 0.01" group size but wouldn't say how they did that. Another thing is that they only shot certain rifles, or types of rifles.

The point is that what we reload and train for is completely different from what is achievable under warehouse conditions.

The OP asks about case capacity and groups; one needs to leave a little room for all the extra factors which the warehouse shooters eliminated.

I have wondered whether they achieved their best results with a single brass case reloaded over and over.

Maybe time to try that?

If you have ever pulled a few rounds of factory ammo and weighed the charges, ...

Out of interest, what was the average charge weight, and the variances.

Was it ball or extruded.

It'll help me understand how the powder measures work on the commercial machines.

I did not take note of the charge weight as such as no one exactly knows what powder they used, but I did not see any ball powder. I was only interested in the variation.

Average charge weights were all around 42.5gr to 43.5gr if I remember correctly. The Berger ammo were the best at +or- 0.2gr. ADI and GGG were all around +or- 0.3gr. Basically what you would get if using a good Harrels powder measure. Velocity wise we were looking at SD between 10 and 15 over 10 shots for the Berger and ADI. Apparently this is excellent.

The Sako hunting ammunition had a charge weight variation of almost a grain! To say that I was disappointed after paying R1100 for 20, is an understatement. Grouping was around 1 MOA, but the 3 round ES was 65 fps! I pulled all those, averaged the load and reduced it by 0.3gr. That reduced the 3 shot ES to 12 fps.

What the exercise above made clear is that most of us reload much better that we can shoot. The precision in reloading that we pride ourselves in rarely translates to real world performance. And the variation that most see on paper are overwhelmingly shooter or rifle induced.

That variation agrees with my observations for volumetric dispensing of extruded powder, the percentage variation increases with the size of the extruded powder grains.

The new Lee Perfect Powder measure can give better consistency with extruded powders than the Harrel, by design. But the Lee is plastic and the Harrel is expensive, and so the comparison usually ends there.

The new Lee Perfect Powder measure can give better consistency with extruded powders than the Harrel, by design. But the Lee is plastic and the Harrel is expensive, and so the comparison usually ends there.

I tested my well worn lee perfects consistency as a side distraction while developing an accurate 12G slug load. My observations mirrored yours exactly. The measure is superbly consistent. With S121 it dropped charges all day that were well inside of 10th of a grain, i.e. variation within the thickness on the zero line of my RCBS scale. It was less consistent with MP and MS but was still slightly better than my very much more expensive Lyman measure.

The only improvement needed for the Lee is an internal baffle system. As it is now, the weight of the powder in the hopper cause slightly heavier charges when the hopper is full as opposed to empty.

A baffle system that only allow a low poder head increases the consistency guite markedly.

The only improvement needed for the Lee is an internal baffle system. As it is now, the weight of the powder in the hopper cause slightly heavier charges when the hopper is full as opposed to empty.

A baffle system that only allow a low poder head increases the consistency guite markedly.

480BC carries aftermarket ones as do a few of the low volume 3D printing guys like like Kevin at Bushmunki. I've never bought one as I haven't run into the issue yet as I keep my powder filled to a 20mm band about two thirds up.

A simple fix for spreading propellant column weight. Strip of plastic (you will have to find right type) about 13 mm wide, bend it so it makes a "v" thats wider than your propellant tube. Insert that into the tube over the outlet hole and when it springs back you will have a "V" over outlet. Place another across the first, it will be held higher by its width touching the first one.
Not being round in fitting allows powder through having a flat surface stops down weight on contents.
The "V" must be long, like "v" in victory fingers.

The only improvement needed for the Lee is an internal baffle system...A baffle system that only allow a low poder head increases the consistency guite markedly.

The Lee Perfect Powder measure alleviates that effect to the point where the height of the powder in the hopper does not measurably change the charge weight.

The powder is flowing to the side, and filling up a narrow tube.

By design, you get much more consistent fill when powder flows through a narrow opening to fill, as opposed to being dumped.

I've got a few powder baffles that have collected over the years, I don't use them because I trickle to weight.