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Old October 2, 2022, 09:09 AM   #26
Jim Watson
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Quote:
I don't think the 223 Rem can produce enough velocity to cause these two effects on .224" bullets, though.
I don't know if it was core slip or simple centrifugal (centripetal) force, but when I was trying to make a .223 into a Long Range rifle with 6.5 twist and 90 grain bullets, it would disintegrate a 75 gr bullet in flight and I actually got C shaped impacts from BENT 90 bullets (when I got close enough to the target to catch a few.) I changed from Sierra to JLK and Berger bullets which were strong enough to stand the gaff, and accurate, too.
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Old October 2, 2022, 01:40 PM   #27
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Great post again (#25) Unclenick.

I knew about the bullet disintegration thing. One of my manuals (Speer, I think; but it could have been Sierra; it wasn't Hornady) cautions about excess velocity with high-twist barrels, using light weight and construction "varmint" type bullets.

I've have done load work ups with 55gn varmint bullets. I stopped at 2800 f/s - I figured that's plenty anyway.

I also load Hornady's FMJ-BT 55 grainers. I figure they are of a stronger construction than the varmints. It's moot however, cuz I use the same charge weight and the resulting velocity is the same 2800-ish f/s.
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Old October 2, 2022, 02:47 PM   #28
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I may have missed someone mentioning this reading thru this post, but no one mentioned that 556 brass wall is thicker thus increasing higher pressure vs .223 remington, I thought the cases dimensionally were identical? except for case wall thickness. I didnt know they had different leads.

Im assuming thats why we have 556 brass and 223 remington brass. Was surprised no one mentioned this???
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Old October 2, 2022, 03:42 PM   #29
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That is because 5.56 brass is not thicker. That is overspray myth from 7.62 where is is true.
Starline makes 223 and 5.56 headstamped brass. The metallurgy is different to make the 5.56 head harder. But the deminsions are identical.
https://www.starlinebrass.com/556x45mm-brass
Also, weighing cases has shown 5.56 to be lighter as often as not. Scroll down to the table.
https://www.accurateshooter.com/cart...guides/223rem/
There are other common misconceptions. This link is from MetalGod:
https://www.luckygunner.com/labs/5-56-vs-223/
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Old October 2, 2022, 03:49 PM   #30
akinswi
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I looked it up

5.56 NATO case capacity: 28.5 grains H2O
223 Remington case capacity: 28.8 grains H2O (+1.1% compared to 5.56 NATO)

so its not much of a difference
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Old October 3, 2022, 10:54 AM   #31
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It's got a tolerance and is not fixed at specific values that is consistent. Follow the second link Marco put up and scroll down about 1/4 of the way, and you will find a table showing the two highest measured case water overflow capacities at the time it was written were for LC'06 and WCC99 at 30.6 and 30.5 grains, respectively.
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Old October 3, 2022, 03:08 PM   #32
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I've weighed 223 and 556 brass on a milligram scale.

Most 223 brass hovers right around 6000 milligrams (6 grams); usually a little less 5960-ish, that sorta thing.

I don't have much 556 brass, but most exceeds the 6k milligrams; usually a little over, 6030-ish.

I have a lot of Frontier 556 brass however, and they weigh out just like the 223 stuff.

So I guess it depends on the 556 brass.

(YMMV; as my sample was only about ten different brands.)
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Old October 3, 2022, 03:50 PM   #33
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Unfotunately, weight is not a consistently reliable capacity indicator because things that don't affect capacity, like the thickness of the rim, depth and thickness of the extractor groove, and the extractor relief angle, all have tolerances that affect brass weight without influencing the internal capacity. Additionally, different makers use different alloys with a difference in density. The last time I looked at how the two correlate was in 308, and there the capacity followed the weight to within about ±20%. So actual water capacity weight measurements are about the only way (sorry, couldn't resist) to go.
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Old October 3, 2022, 05:30 PM   #34
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I agree with UN completely. The only time case weight will make a consistent difference in case volume is when that case weight differs by many grains 10+ . If you have one case that weighs 175gr and another that weighs 160 . The 160gr case will almost always allow for more case volume . I’ve done a good bit of this type of testing in the past with 308 cases and I rarely see a +/- 3gr in case weight . There are exemptions for sure and even then its 10gr or less . I have some RIP that weigh in the mid 170’s with most LC , Lapua and Fed weighing in the low to mid 180’s . I also have some Win cases that are weighing in the low 170’s to high 160’s . The Winchester cases held more H2o but don’t remember how much more . I haven’t looked at all that data in awhile , not even sure where its at or where I put the brass if I wanted to test again . I have so much brass it became hard to organize to that degree . It’s here somewhere marked and if I come across it I’ll try to set aside .
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