223 testing results

[Nathan]

There is a lot of negative press about LC brass in here. I simply sorted some once fired by year, fully prepped it, loaded up a variety of loads behind Hornady 75’s. Shot all groups under 1” and my any under 0.75”.

[tangolima]

Originally Posted by Nathan

There is a lot of negative press about LC brass in here. I simply sorted some once fired by year, fully prepped it, loaded up a variety of loads behind Hornady 75’s. Shot all groups under 1” and my any under 0.75”.

I tried, but was not able, to sort LC brass by year. I ended up with a few in each of many buckets. The mixed year LC brass don't work well. Weight varies from 91 to 98gr. Even with close weight sorting, sd in MV is disappointing. I reckon it would be more efficient to weight sort other brands.

-TL

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[603Country]

These days I normally use Lapua and Norma brass, though I did recently get some Starline. In past years, when I was a lot more serious about accuracy, specifically in my 220 Swift, when my small supply of Norma brass wore out, I could only get Winchester brass. When fully prepped, the accuracy was every bit as good as when I was using Norma, and maybe even better. But the problem was prepping the brass, which I tired of. So, back to Norma brass. My point is that maybe the LC brass, weight sorted and fully prepped, might be all a fellow needs. Of course, need is subjective…

[kmw1954]

Back a couple years ago when I started shooting and reloading 223 I was able to obtain a lot of once fired brass from many manufactures. Tons of LC with years stamps from 14 to 21. So I did a little unscientific testing and loaded up 20ea of LC, FC, PMC, GFC and Norma. All were loaded exactly the same with the same components. Shot 10 each over a Mag Speed chrono and 10 each at 3" targets at 100yards. The smallest groups and the most consistent speeds were the Norma followed by the PMC followed by the GFC. So after that little test all crimped primer LC brass went bye-bye.

Now after all this time all that is on my bench is 600pcs of Norma, 1k pcs of PMC and now 350pcs of once fired Hornady that another friend has gifted me.

[Shadow9mm]

I have been using LC as I was gifted a rather large supply if it. I have several thousand pieces of it, around 1/2 of a 5gal bucket.

I have never tried "nice" brass. I want to try some Laupa at some point, but Its expensive and hard to justify putting into a mid tier AR with a medium contour barrel.

[tangolima]

I think LC will work if you sort head stamp by year, followed by weight sorting to within 1gr. The first step is difficult for me as I pick up brass at range. Not enough to fill each bucket with meaningful number of samples for weight sorting.

I have FC, wolf and win, none is boutique brass. My rifle is lower than mid range. Bear Creek arsenal upper with Wilde chamber for $250. Lower is $60 no name deal. The trigger is perhaps the only brand name product. It is a Jewel 2-stage that has been discontinued for many years.

-TL

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[Metal god]

Tango talk with Many at South Bay he’s the care taker . He can get you LC cases from the same lot . All the LC brass there is from the military and when they come out to shoot they shoot thousands of rounds at a time . Those all are likely pulled from the same pallet of ammo . Meaning likely all come from the same manufacturer. When are we going to Pala haha .

[tangolima]

Ah good idea. I went there last week. The navy was there firing away their machine guns. I thought I was in a movie. I will talk to the man. Thanks.

I have been getting myself ready for the long range at Pala. Shooting 6.5mm grendel at 300yd before the storm rolled in. Wind was gusty and chaotic. It was 6" to left and 6" to the right when I switched to 5.56. Vertical was excellent with my sorted FC and Wolf brass. I was delighted.

I want to be a bit more ready before heading out to Pala. It is $40 a session. Need to have enough gun and ammo.

-TL

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[Nathan]

I tried, but was not able, to sort LC brass by year. I ended up with a few in each of many buckets. The mixed year LC brass don't work well. Weight varies from 91 to 98gr. Even with close weight sorting, sd in MV is disappointing. I reckon it would be more efficient to weight sort other brands.

What is weight sorting telling you? Seems like most in the precision sports have dropped that practice….

[Shadow9mm]

Is should in theory, given that the case is sized and trimmed, tell you how uniform the cases are. If the external dimensions are the same, and the volume of brass is the same, in theory the cases have a higher chance of being uniform in relation to each other.

[603Country]

Might be a good point in the discussion to ask how much accuracy folks are wanting from the LC brass. What’s good and what’s not good? Nobody has said that they can shoot 1/2” groups with Lapua but only 1 1/2” with Lake City.

I have a good bit of LC brass, but have been slowly resizing and trimming and removing primer crimps. I haven’t used any of it yet. Just saving it for later use. And I wasn’t planning to do any serious prep, like neck turning and flash hole cleanup. If I was set up for reloading, I’d go load up some rounds and see what I could do group-wise. And then weight sort some and try again. Might be interesting. Maybe then I could really prep some weight sorted brass and try that. Then compare it all to my Lapua loads.

[Metal god]

I did a good bit of water volume test with 308 cases several years ago . This was with Lapua , FC ( Fed ) , and multiple year lots of LC brass . I don’t have the data in front of me but some LC years were just as consistent as commercial brass . LC 14 being the worst .

As far as accuracy, I’ve shot plenty of 1/2 moa 5 shot groups using LC brass in both 308 and 223 . That said I’ve never shot any group’s consistently in the 1’s 2’s or 3’s with any brass so it seems LC brass is able to shoot as well as I can . I will add I get my LC brass from a place where its more likely then not the LC brass I buy are all from the same lot which may explain my h2o results. I would not expect those same results with standard range pick up or buying randomly online .

[Unclenick]

I also did a bunch of 308 volume and weight measurements at one point. I found weight only predicted the difference in internal volume to within about 20% of the measured value.

[tangolima]

Originally Posted by Unclenick

I also did a bunch of 308 volume and weight measurements at one point. I found weight only predicted the difference in internal volume to within about 20% of the measured value.

Percentage variation in brass weight is not the same as the percentage variation of powder capacity. Here is the equation I derived.

Va=-0.12*Vb

Where Va is percentage variation of powder capacity, and Vb is percentage variation of brass weight.

The constant 0.12 is density ratio between water and brass. Brass is about 8 times denser than water.

That's assuming no variation in brass density (same batch from the same manufacturer). There is another equation linking Va to percentage variation of brass density. It shows a more significant factor, especially for smaller volume brass such as .223 rem. That's why stamp sorting could be more important than weight sorting, or less important for bigger casings such as .308 win.

-TL



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[Shadow9mm]

Sorting by weight can help. Its not going to turn LC into Lapua, but when you have a bunch of lc to use, its better than nothing.

[Metal god]

I thought the idea of sorting brass by weight has been proven to mean nothing or was it weight has nothing to do with volume? I guess I’ll need to go look at my weight and volume data an see what it actually says . Actually I believe I’ve posted that data here in at least one thread , maybe I’ll be able to find that rather then reposting everything again .

[tangolima]

I think first you need to sort by head stamp to make sure close match of material. Brass density variation affects powder capacity more significantly than weight. Then brass with identical head stamp are to be sorted by weight.

Brass density has range of +/-4%. Head stamp sorting cuts it down, to say +/-2%. The corresponding powder capacity variation is +/-0.7% for .223 Rem. I would like to weight sort the brass with matched head stamp to have significantly lower effect on powder capacity, say +/-0.1%. The weight sort range is 0.8%, or +/- 0.75gr for .223. I do +/-0.5gr.

This is based on equations I have derived for .223. It is different for different calibers.

-TL

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[Unclenick]

Originally Posted by tangolima

Percentage variation in brass weight is not the same as the percentage variation of powder capacity.

That is correct, but my point was the difference in brass weight is also not reliably proportional to the difference in powder capacity. The head tolerances alone can cause several grains of weight variation before you even get to the part of the case that holds the powder.

What I did, specifically, was resize and trim mixed headstamp 308 cases. I then weighed the cases and divided the case weight differences by the specific gravity of cartridge brass (see ρb values below based on this alloy analysis) to try to predict the difference in space made (or taken away) for case water overflow capacity. I then plugged the primer pockets, re-weighed the cases, and then filled them with outgassed water (to prevent bubbles) level with the case mouths (no meniscus), weighed them again, and subtracted the unfilled weight to learn how much water weight they were holding in grains. What I found was that if the difference in brass weight predicted a 1-grain difference in water capacity, the measured difference in water capacity might be anywhere from 0.8 grains to 1.2 grains. In other words, ±20% prediction accuracy is based on the difference in brass weight alone.


Added information for anyone who cares:

LC, ρb=8.53 g/cc
Win,ρb=8.56 g/cc
Lapua, ρb=8.60 g/cc
Norma, ρb=8.63 g/cc
Federal,ρb=8.64 g/cc
Rem, ρb=8.69 g/cc

[tangolima]

Thanks for sharing the density data, unclenick. The variation among those manufacturers is about 2%, which is about half of what I have assumed. Head stamp sorting should reduce it much further.

I see your point on the error term due to variations in the dimensions around the extraction groove. I'm updating my derivations to include it. With powder capacity versus brass weight data points, that error term can be extracted and accounted for.

In the meantime, even with the 20% error, weight sort should still work. We just need to tighten the acceptance window.

Say for .308 win, nominal power capacity is 56gr H2O. If I want to limit the variation to 1%, or 0.56gr, I tighten it to 0.47gr to account for the 20% error. That translates to about 3.7gr acceptance window in brass weight sorting.

So far I found stamp sorting is most critical for .223 rem, which has smaller powder capacity of 32gr H2O. The acceptance window for brass weight sorting is 0.75 - 1gr, and I have to ditch about 50% of the brass I bummed from the range to meet that goal.

-TL

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[44 AMP]

I thought the idea of sorting brass by weight has been proven to mean nothing or was it weight has nothing to do with volume?

Not "nothing" but not "absolutes", either.

Consider this, since the brass is the same size on the outside, and capacity is determined by the size of the inside, the heavier case must have either thicker walls (more brass) OR it has the same thickness walls made up of a heavier alloy.

SO, the heavier brass MAY have less capacity, OR it may have the same capacity and be made of a more dense alloy.

There is a relationship, but its not an automatic one where every batch of cases from every maker can be plugged into a general formula and have accurate results.

I think this is one of those things where formula can predict general trends but actual differences (amounts) must be determined by weighing and measuring the cases you are working with.

Or not bothering to worry about it, and just working up your loads with what you have, specific to what you have.

for example, GI brass is usually heavier than some/most commercial brass, but you can't tell exactly how much of a difference that is going to make only that there will be a difference, the exact amount of which requires measuring what you have.

[tangolima]

I have never paid much attention to head stamp and weight sortings till recently, when prices for everything has elevated. Making everything round count is way to conserve.

-TL

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[jetinteriorguy]

I used to obsess over this stuff but finally quit driving myself crazy over it. All I ever proved was that no matter what I did, with my ability and equipment I’m a solid 1/2-1 MOA shooter. But, I did prove to myself that with good ammo and the right load I’m happy with that. This is pretty easily achieved with good diligent methods but not so totally perfect loading technique.

[zeke]

Once did a test with about 6 varieties of 308 brass with the same powder charge, primer firearm. With a lower than max load, the heavier cases consistently gave a slightly higher velocity, and almost a direct correlation between weight and velocity difference. Albeit the rounds per case were limited. Fed brass was the heaviest commercial brass weighed (close to milsurp), and Win the lightest. The main point being to consider what brass was used in load manuals when working up a load.

And am always wondurus about the capability to accurately measure the weight/volume of water in a case. Certainly the density of brass may matter, but given the amount of brass in the cases involved, gotta wonder how much it matters.

[Unclenick]

You can see from the numbers I gave that the range is about 2% density difference. 308 Win cases are in the 55-60 grain water overflow capacity range. Out of that, the alloy can be responsible for up to about 1 grain of capacity difference. So, while I gathered that data off of Matweb, I still think the head tolerances are the big noise.

Here's an illustration of the SAAMI minimum dimension and maximum dimension case head:

[tangolima]

Unclenick. Because brass is much denser than water, it takes about 8gr of brass to make one grain of water. I don't know the average weight of .308 brass, say 150gr. 2% is 3gr or less than 0.5gr water equivalent. That's what I meant the percentage variation in brass weight cannot be directly translated in powder capacity.

-TL

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