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Lake City .223 brass vs production date

Out of curiosity a couple weeks ago I did some cutaways for comparison.

i-2fCGw3z-X2.jpg


Measured the web thicknesses at the flash hole.

Top to Bottom:

Rim Rock .0815"
LC 75 .071"
LC 87 .0665"
LC 84 .070"
WCC 70 .061"
WCC 91 .0735"
TW 68 .060"
CJ 9 .070"

I don't know who manufactures the TW & CJ head stamp.

The Rim Rock head stamp is from a small manufacturer in Central Oregon that has disappeared. It was new 55g Vmax I used for sage rat hunting (I have 4k+ pieces). I still have some back stock and tested it in my Tikka Varmint with good results. Not 69g Federal GMM accurate but close, neck and neck with Black Hills Blue 60g Vmax.

I don't have a ball mic to accurately check neck thickness variation though after chamfering necks and measuring with calipers the Rim Rock appears to be more uniform than the others.

Looks like my hoarding may have paid off.... for once. :D
 
TW was “Twin Cities Army Ammunition Plant”. It was run by Federal ipuntil it closed. It has since been demolished.

CJ is Norinco from China. Some people like it. I use it in specific guns. There are better
 
Found some LC 76 Nickel 223/556 in the attic not long ago.. The 40 or so l did weigh had a 1.1gr spread with a 90gr average.. Not up to Lapua standards, but good enough for MY limited standards shooting a local Factory Varmint match in years past..
Lapua brass is in a class by itself however... l shoot IHMSA pistol silhouettes and have been since the late 70s... l shoot Revolver class. The UNLIMITED class is where the accurate guns live. These are mostly XP100 design single shot bolt pistols limited to 14'' barrels.. Most calibers are PPC or BR based ctgs... Virtually ALL the lnternational and AAA shooters use Lapua Brass.. l don't know what the accuracy capabilities these Unlimited Bolt Guns are. l do know they are built to pretty high standards... Same brand barrels seen on Bench Rest rifles are on IHMSA unlimited guns...LAPUA brass is used by BOTH
 
243winxb said:
LC Brass -



NO. Not with mixed head stamps, even marked with the same year. If ammo is of the same lot, from same box, then it may be ok. Range brass thats sorted by year and weight is a waste of time. Imo. :)

Scamp markings
Some US GI cartridge cases are run on SCAMP (Small Caliber Ammunition Modernization Program) lines. This is HIGH speed cartridge case making equipment. Several lines of SCAMP machinery may be used to run cases thru out the year, or on the same lot/year of ammo. Those dots identify which SCAMP line. 24 stations are used on the SCAMP machines, Shoot the LC brass till the necks split, then recycle it. Its not match grade brass.View attachment 1137017
Click to expand...


Can this brass be purchased new? If so where at?

Thanks,
Don Dunlap
 
OK, going back to the first page with the bar graphs, charts etc, which I found to be noteworthy, I ran across a pet peeve.
That is the statement of xx "Rockwell". Having spent more than a few years turning handles, occasionally case hardening or heat treating several of the more common metals, I grind teeth at the above Rockwell reference. B Scale, C Scale orrr? One uses a diamond, one uses a ball for indentation. But, I'll soldier on. :cool:;) I feel better, I think.:rolleyes:
 
Uncle Ed said:
The 5.56 cases are made of a harder grade brass in the right places and not thicker brass. And using the harder brass adds to its case capacity.
Click to expand...

I'm not sure you're saying what you mean and I couldn't blow up the text to read.
I really dont understand how two different copper properties are melded into a single case. Do they use two different sheets of material when mfrg?
I think I'll head over to the Tube and see what I can see.
However, it seems I've heard, read that the properties are regulated by the area of heat application, temp and length of time.
 
I've been prepping a 100 of the Rim Rock cases for load development, uniforming pockets, chamfering flash holes, FL sizing and bumping shoulder to 1.455-1.4575, trim to length, and now checking neck thickness.

Necks range .010-.012 measuring 6 points around the circumference, extreme has been .010-013, the majority (80%) average .0015" variation.

Weighed 20 cases, low 96.25g and high 97.67g, next lowest 96.39g next highest 97.39g.​

How do those numbers sound to you experienced loaders?

i-b4XDH6r-M.jpg
 
Last edited:
Sieg said:
Out of curiosity a couple weeks ago I did some cutaways for comparison.

i-2fCGw3z-X2.jpg


Measured the web thicknesses at the flash hole.

Top to Bottom:

Rim Rock .0815"
LC 75 .071"
LC 87 .0665"
LC 84 .070"
WCC 70 .061"
WCC 91 .0735"
TW 68 .060"
CJ 9 .070"

I don't know who manufactures the TW & CJ head stamp.

The Rim Rock head stamp is from a small manufacturer in Central Oregon that has disappeared. It was new 55g Vmax I used for sage rat hunting (I have 4k+ pieces). I still have some back stock and tested it in my Tikka Varmint with good results. Not 69g Federal GMM accurate but close, neck and neck with Black Hills Blue 60g Vmax.

I don't have a ball mic to accurately check neck thickness variation though after chamfering necks and measuring with calipers the Rim Rock appears to be more uniform than the others.

Looks like my hoarding may have paid off.... for once. :D
Click to expand...
Thanks for digging into this and posting it. It's good to compare my brass's construction, when you did all the legwork!
 
In doing a little more research on the who supplied Rim Rock with their brass I'm of the belief that they sourced their brass through Nosler since both companies were located in Central Oregon (Bend/Redmond area). In the beginning Rim Rock was using the orange tipped Nosler 55g varmint bullet then switched to the V-Max.

So there is a good chance their private head stamped brass is from Norma. Based on the dimension and weight measurements I've taken it appears to be quite close to Lapua quality brass. Also noted in Nosler's history timeline in 1963 Norma became Nosler’s first commercial loader.

https://www.nosler.com/brass/

If that's the case I'm glad I saved all that brass over the years!
 
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