Stupid question about 5.56 brass

[Jackpine Savage]

I purchased one of the 1000 round bulk packs from Fleet Farm that had these crimps. The brass was LC 13. I think it was labeled Federal M193, not the American Eagle stuff. I purchased another box last fall and it had the old style crimp.

[steve4102]

5.56 brass has a thicker wall, which means a smaller case volume. If you're loading near max, that becomes an issue.

I think this is an old wives tale.

http://www.6mmbr.com/223rem.html

You are correct, it is an internet myth or wives tail.

Look closely at the link provided above. You will see that Military LC a WCC have the highest case capacity of them all.

You will also notice that there is no direct correlation between case weight and case capacity.
Example: The Military WCC 99 weighed 95.5gr with 30.5 capacity.
, The Rem 223 brass weighed 92.3gr with 30.4 capacity.
In this example the Military case weighed 3.2gr More yet it held .1gr more in case capacity.

Another example; PMP brass weighed in at 104.5 with 29.9gr case capacity
, FNM brass weighed in at 97.3gr with 29.8gr capacity.
In this example the PMP brass weighed a whopping 7.2gr more than the FNM brass yet it had .1 gr More case capacity.

This is my personal capacity data.

GFL(223) dry weight-102.4gr
With H20-131.4
Case capacity in grains of H20-29gr

Remington(223) Dry weight-95.2gr
With H20-125.1gr
Case capacity in grains of H20-29.9gr

LC(5.56) Dry weight-96.3gr
With H20-126.7gr
Case capacity in grains of H20-30.4gr.

As you can see here my 5.56 brass had more case capacity them my civilian 223 brass, even though it weighed more than the Rem 223 brass.

Sierra has also done testing on 223 vs 5.56 and come to the same conclusion that 223 brass does NOT always have more case capacity.

The conventional wisdom to reduce loads with military brass is familiar to most reloaders and is generally good advice. The rationale here is that the military cases tend to be somewhat thicker and heavier than their civilian counterparts, which in turn reduces capacity and raises pressures. This additional pressure normally requires a one or two grain reduction from the loads shown in most manuals or other data developed with commercial cases. While this is most often the situation with both 308 Winchester and 30-06 cases, it is less true with the 223 brass. We have found that military cases often have significantly more capacity than several brands of commercial brass. Again, take the time to do a side-by-side comparison of the cases you are working with and adjust your load as needed. There may be no need for such a reduction with the 223. Know your components and keep them segregated accordingly.

Link.

http://www.exteriorballistics.com/reloa ... reload.cfm

[OldmanFCSA]

About 2006, LC changed their brass.
We 50BMG shooters noticed it as case wall and neck wall thickness dropped from 0.023" to 0.019" thickness.
If this was applied across all of their military cases, I would agree with you.
However, I have RA-70 7.62X51 cases that are much heavier than my REM 308 cases.
I will weigh them again and post the results, I do not CC my cases anymore - too much hassle for FUN shooting.
If I only loaded for one or two rifles, I would, but not for the 40+ cartridge types I currently load.
I probably should for my 50's, but have had good time just weighing cases and shooting lightest to heaviest.

[JTapper]

An "off the record" and not guaranteed response from someone at ATK was that the M193 and M855 brass all comes off the same line (obviously). They stake the primers for M855 due to the hotter load and heavier projectile. Supposedly military buys a ton of M855 and it was to prevent primers from popping out. Most of the rounds you buy off the shelf were produced in Lake City and packaged in Federal packaging.

The only difference in the XM193xxx part numbers is the packaging configuration. All rounds are identical, off the same line, with the same load, same projectiles, meeting the same quality standard.


Cliffs Notes:
Once swaged they should be able to be reloaded witout issue.

I AM NOT A RELOADER. Just someone interested in reloading that has been doing a lot of reading and discussing with experienced reloaders.

[steve4102]

About 2006, LC changed their brass.
We 50BMG shooters noticed it as case wall and neck wall thickness dropped from 0.023" to 0.019" thickness.
If this was applied across all of their military cases, I would agree with you.
However, I have RA-70 7.62X51 cases that are much heavier than my REM 308 cases.
I will weigh them again and post the results, I do not CC my cases anymore - too much hassle for FUN shooting.
If I only loaded for one or two rifles, I would, but not for the 40+ cartridge types I currently load.
I probably should for my 50's, but have had good time just weighing cases and shooting lightest to heaviest.

According to the Linked article from Sierra above, 30-06 and 308/7.62 Military brass has less case capacity than civilian brass. They specifically call out 223/5.56 as different.