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I know it's Thanksgiving, but research must go on! :yup: But, HAPPY THANKSGIVING EVERYONE!!! Or in my case, Happy Thinksgiving :tongue:

I chrono'd the same charge in three different brands of cases, Hornady, Lapua, and Winchester. Fifteen shots per case; here's the result:

It's interesting that Hornady and Lapua are so close - 9 fps, while Winchester is a whopping 45 fps slower than Lapua. I believe, as in not confirmed - YET, this is due to case volume differences.



There are two things apparent from the table, Lapua produces higher velocities, albeit at higher pressure, and Lapua cases were the clear winner in the velocity consistency.

I would note that it was one shot only that drove the ES of the Winchester so high. Eliminating that one shot would reduce the Winchester ES to 54 fps which is right between the Lapua and Hornady. The question is, can the elimination of that one shot be justified? I don't know. It was pretty much an outlier at 2521 fps and the nearest to it was 2544 fps - a difference of 23 fps. But, moving on...

When I started sizing the Winchester cases, I noticed the expander didn't even drag on the Win. case mouths :blink:. I use a Hornady Match grade sizing die because it sizes cases larger than the 223/556 small base die and it lets me use bushings to set the OD of the case neck so the expander can set the final neck size. For Lapua and Hornady, I use a 0.244 bushing. That wasn't working for the Win. brass. So I wound up with a 0.242 bushing and that was just about perfect for the Win. brass! What does it mean?

Well, first of all, the fact that the Win. cases produced 45 fps less average velocity strongly suggests that the Win cases have more volume and the fact that a smaller bushing had to be used to set the neck strongly suggests the brass is thinner, which would add volume to the cases IF the brass is thinner throughout.

So, I had the thought, I should increase the charge weight a bit for Win brass to compensate for the slightly larger volume. It would be pretty arduous to do this blind by reloading and testing, so I started with QuickLoad. I set the case volume for the Lapua brass to give me the measured velocity I got with the Lapua brass. Then I increased case volume until the velocity decreased to the measured Win case velocity. Naturally, the peak chamber pressure is lower with the Win brass.

So then I thought, hmmm, what if I increase the charge for the Win case until the theoretical velocity matches the Lapua velocity! You see what happens when I think, Hmmm? :tongue:

So I increased the charge from 23.3 gr incrementally by 0.1 gr until I got to 23.7 gr which matched the Lapua velocity to 2 fps. Then I noticed for the same velocities, the pressure was less for the Win case - that's significant! I had another hmmm thought which was, what if I increase the charge until the Win pressure matches the Lapua pressure instead of the velocity! I did that! It only took one more 0.1 gr to match the pressure, well the Win pressure was a bit lower still, but another tenth would put it over the pressure and I didn't want that.

23.8 gr in the Win case vs 23.3 gr in the Lapua case, the Win case would theoretically generate a bit less peak chamber pressure, but the Win velocity would be about 13 fps faster than the Lapua.

So in summary,

  • The Win cases have more volume than the Lapua and Hornady - has to be due to slightly thinner walls.
  • The thinner wall is supported by the fact that the necks require a smaller bushing to set the necks properly
  • The Win cases shot slower for a given charge than the Hor or Lap
  • In theory, adjusting the Win charge to produce the same velocity as the Lapua will produce less peak chamber pressure
  • In theory, adjusting the Win charge to produce near the same pressure as the Lapua will produce slightly higher muzzle velocity
In summary of the summary,
  • I need to load up and test this! :yup:
 

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I can tell that mowing season is over. Nobody has this kind of time on their hands when the grass is growing. That aside, I think the theories hold water. I wouldn’t necessarily expect Win brass to be thinner, next to the other two, but if one of the three were going to show as “less”, I’d guess it would be Winchester. Bulk brass prices probably support that.
 

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I'm loading the Win cases now....

Just so happens I have 25 Lapua cases already loaded with 23.3 gr of 8208 and I'm about to have 25 Win cases loaded to 23.8 gr of 8208 - then the theory goes to the field!
 
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Very interesting. I still have 1400 pieces of "virgin" Win brass. I'll be watching to see the net result.
 

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Tangle, I would take some sample weights of your 3 brass varieties. Bet we know whose cases are the lightest!
Good idea! 5 Winchester cases weigh 478.8 gr; 5 Lapua cases weigh 497.6 gr.

Winchester average case weight = 95.76 gr
Lapua average case weight = 99.52 gr

Average difference in weight (per case) = 3.6 gr or 3.9% difference in weight per case.
 

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Very interesting. I still have 1400 pieces of "virgin" Win brass. I'll be watching to see the net result.
This afternoon if all goes well.
 
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Tangle, NASA is looking for you!
 
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Lapua, Starline and Lake City brass I keep. Everything else goes in the sell bucket. Hornady makes decent brass, but I don't have any in 223. Rem, Win, Fed is just crap. Over the last couple of years, I've been buying Starline over Lapua 223 brass, the price difference is significant and the quality nearly equal.
 
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Ohhhh, now you need a graduated cylinder and pipette to measure the case volumes! With each one, micro-etch the rim with microliters and tailor powder charge for every round. THAT'S the ticket...
 

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Here are the results...

The charge data/components are at the top; the stats are next; then the actual velocities measured by LabRadar.

I shot these in 5 shot groups - 5 Winchester, then 5 Lapua, and repeat until all 50 rounds are shot.

Let me draw your attention to shot #4 in the Winchester column. I don't know what happened here, but this velocity is waaaay out of line with the other 24 shots. I would not consider it a statistical possibility, but rather an anomaly. With that shot included, the Win ES was 81 fps; without that one anomalous shot the ES is 45 fps which is what you see in the table below.

However, I will show you what the graph would look like with that shot. This is a graph with the Win data sorted from low to high:



Quite a drop isn't it? And here's the data table and graph with that one shot eliminated:



This graph shows the two sets but with the velocities sorted from low to high. I was a little surprised to see how much faster the Win was than the Lapua. I was expecting them to be pretty close to the same.



You may notice the Win line starts at 2 instead of 1. That's because I eliminated that low velocity.

Neither cases showed pressure signs. I even had a guy at the range take a look at them and he almost instantly said, "I run a lot hotter than that."

Neither showed acceptable, consistent accuracy. That's likely because I was simply not at the optimum charge for the gun and bullet. I expect, if I tune the charges a bit, I would get better accuracy and even better ES.

Like so many tests, this one simply indicates a few more tests need to be done. However, given the velocity data, the Winchester brass outperformed the Lapua brass. That could be because of the heavier charge in the Win cases.

While there were no pressure signs, I believe the charges shown, esp. the Winchester is simply too hot, so I'll run some incremental charges and see what happens.
 
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Shooting a 338 lapua for a short while now. Will not be doing any reloading for it until my Son gets back. Good thing is factory ammo is becoming more popular and prices coming down.
 
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One addition...

I don't like to eliminate an event, in this case, a velocity outlier unless there is pretty strong justification to. It appears there is plenty of justification for eliminating that one low shot from the 25 Winchester case shots. Below is a distribution graph that is used to illustrate how the "events" occur. The dash-dot line is the average velocity WITHOUT the low velocity, although there isn't that much difference in the average velocity, with it or without it. The average with it is 2629 fps; without it the average is 2631 fps - a mere difference of 2 fps.

So the dash-dot is the average. The dashed lines to the left of the average line are the 1 SD, 2 SD, 3 SD and even 4 SD points. Here's what it means:

In statistics we expect 68% of the events (velocities) to be within +/- 1 SD (standard deviation); 95% of the events will be within +/- 2 SDs; 99.7% of the events will be within +/- 3 SDs; and 99.9% of the events to be within +/- 4 SDs. Notice in the graph below, that point I want to eliminate is well outside the 4 SD point!

Hence, I believe I am justified in eliminating that velocity. If for no other reason, it is very unlikely to occur.

 
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