LC, RP, FC Case Comparision (223)

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Will Lee

New member
I have read on my 4 favorite Forum (many times) that Lake City cases are thicker therefore have less volume so charges need to be reduced slightly to avoid excessive pressure.

Being retired and with tons of free time on my hands I did a little test today to satisfy my own curiosity.

Here is the data (all cases were SS Media tumbled and Ultrasonic cleaned with new CCI 450 primers). All cases were randomly selected. All cases weight on RCBS digital scales. Also all of these cases have been cycled several times. All cases trimmed to 1.750.

RP
96.0
95.5
94.9
94.1
96.6
AVG=95.48 ES=2.5

FC
96.0
96.4
96.2
96.5
95.9
AVG=96.2 ES=.5

LC-08
95.2
95.3
95.3
95.9
96.1
AVG=95.56 ES=.9

Selected 1 case from each group of the same dry weight (almost) and filled them with water.

LC = 96.1 = 126.4
FC = 96.0 = 126.5
RP = 96.0 = 126.3

Needless to say there is some contradiction in what I've read and what this data shows.
 
M

moxie

New member
I think what you've shown is that the differences between case brands don't amount to as much as some would say. Some of the differences in weight you've shown could be due to differences in the copper/zinc ratios, copper being a bit heavier/denser, as opposed to thicknesses in case walls. Interesting excursion! Thanks.
 
W

Will Lee

New member
I think what you've shown is that the differences between case brands don't amount to as much as some would say. Some of the differences in weight you've shown could be due to differences in the copper/zinc ratios, copper being a bit heavier/denser, as opposed to thicknesses in case walls. Interesting excursion! Thanks.
__________________
If you want to shoot...shoot...don't talk! Tuco
Click to expand...

Hey moxie, love your signature line, my favorite movie of all time.

I am a hunter first and foremost, I go to the range to test loads and keep my shooting skills sharp. I have been real anal about cases due to what I've read on this an other forums. I am going to load those case with my favor load and test them. Will post result with pictures here.
 
2

243winxb

New member
Doing your own testing-The only way to know.

I have some MKE 08 that weights 102.4 gr to 99.2gr, heavy for the 223/5.56. BHM runs 95.6 to 93.0 gr. Normal is 96 to 93 grs. for most brands. IMO. :)
 
G

griz

New member
That's been my experience in 223, with both LC and WCC brass. However 308 military brass does weigh more.
 
M

m&p45acp10+1

New member
If I were to rub off the head stamp on all of my .223 brass I doubt that with my shooting I would be able to tell much (if any) of a difference in performance at 100 yards.

Though I tend to avoid R-P brass. The rims on the ones that I have picked up were thin. Team that up with the fact that they were AR fired. The rims on most were bent, and even after a bit of straigghting they would wobble out of my Lee Case Trimmer. Also the only two pieces of brass that have ever stuck in my dies were R-P. The rims tore off of both, and both were lubed.
 
H

HJ857

New member
Great test Will, thanks for posting the results. I've tested LC Nato and non Nato plus R-P brass and found that R-P has no consistency at all. Your R-P sample is a lot better than mine.

I've also tested matched LC and LC Nato against truly mixed brass and do find the matched cases shoot a tiny bit better. For my use, it's not enough of a difference to matter.
 
W

Will Lee

New member
Great test Will, thanks for posting the results. I've tested LC Nato and non Nato plus R-P brass and found that R-P has no consistency at all. Your R-P sample is a lot better than mine.

I've also tested matched LC and LC Nato against truly mixed brass and do find the matched cases shoot a tiny bit better. For my use, it's not enough of a difference to matter.
Click to expand...

Hey HJ857,
After reading your response I went back to my container of RP brass and weight about a dozen more cases. They were all over the place, as much a 4g ES. As I have well over 1000 cases of once fired LC military cases the RP cases, about 150, went into the **** can.
 
U

Unclenick

Staff
It is only in .308/7.62 cases that you find a big difference between commercial and military brass. In particular, military 7.62 NATO cases seem to run in the 178-186 grain range, while commercial brass runs from as low as 156 grains (Winchester) to as high as around 174 grains, but mostly is around 170 grains. .223/5.56 has never had significant volume or weight differences between commercial and military. The military drawings include a sectioned case with hardness specs at specific places in the brass that SAAMI specs don't include in their ANSI standards, but otherwise they are the same. The military specs don't care if you control hardness by alloy or by work hardening. The small differences you detect are almost invariably due to small exterior dimensional differences such as rim diameter and thickness or angle of the taper to the extractor groove from just ahead of it.

Note, too, this information changes lot to lot. For another recent thread I weighed ten new, never loaded Lake City cases and ten new, never loaded Winchester cases on my lab scale that resolves 0.015 grains (0.001 grams). I got:

Code: 
LC 5.56     92.19 grains
Winchester  93.30 grains

So, my LC lot is different from Will's. Since those were both new, never loaded sets of brass, no residue of any kind was in or on them.

The density of 70:30 cartridge brass is given on matweb.com as 8.53 gm/cm³. So if two cases have identical external dimensions, the difference in case weight divided by 8.53 will be the difference in water capacity. If my Lake City and my Winchester have identical exterior dimensions, on average they will have:

(93.3 -92.19) / 8.53 = 1.11 / 8.53 = 0.13 grains difference in water capacity. Typically powder charge difference works out to be around half the water capacity difference to get same velocity in a high power rifle, so this is well within the error of most powder dispensing systems, including electronic ones. Nonetheless, I still segregate the cases by case headstamp because, if the necks of one lot have a firmer grip on the bullet than those of another due to different annealing temperature or just due to different loading history, it may increase velocity spread enough to show up on a 600 yard target. Even if not, sorting by headstamp makes load history and retirement easier to track.
 
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