cartridge case specs

[2Tite]

Does anyone know with certainty what the range of Rockwell hardness cartridge brass is? What type of brass is specified for cartridge use? Source for small quantities?

[kywoodwrkr]

"ASM HANDBOOK Volume 2 has hardness data (Rockwell B, HRB)for half-hard C36000. Some typical values for rod range from 75-80 HRB. Table 4 of ASTM E 140 shows approximate hardness conversions for cartridge brass (70Cu-30Zn) as follows:

75 HRB ~ 121 HB
80 HRB ~ 131 HB

copper.org also has the data from ASM HANDBOOK Volume 2."
FWIW

[deltaenterprizes]

What are you planning to make?

[S.R.Custom]

Small arms cartridge brass is Copper Alloy UNS No. C26000: Rockwell B82

http://www.anchorbronze.com/c26000.htm

http://www.astm.org/Standards/B129.htm

[kywoodwrkr]

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA497469&Location=U2&doc=GetTRDoc.pdf
and conversion link
http://www.hardnesstesters.biz/article/008.html
Finally found this link-again!
Good luck.
Dave

[Cap'n Morgan]

You'll need the correct temper for the material. Check this site for temper codes:
http://www.matweb.com/reference/cutemper1.aspx

The site is excellent for finding data for every possible alloy. Navigating the site takes a little getting used to. In your case search: Materials - Nonferrous Metals - Copper alloy -Brass.

Notice that cartridge cases vary in hardness from head to mouth with the case head being the hardest.

http://img33.imageshack.us/img33/9684/hardness.jpg (http://img33.imageshack.us/i/hardness.jpg/)

[kywoodwrkr]

My view of the hardness graph of the M855 cartridge case is that the area about 1/3 the way from the base to the mouth is the hardest.
This would confirm to that area being worked more than the base and the mouth being annealed.
I've been trying to get a process together where I can test the hardness of the brass in the various positions.
Decided I couldn't afford even the portable hardness testers used for tubular brass!($900+)
So am going to redo an old Rockwell machine and see what I can work out with it.

[S.R.Custom]

My view of the hardness graph of the M855 cartridge case is that the area about 1/3 the way from the base to the mouth is the hardest.

Indeed. And it's entirely consistent with my experience in working with this case....

When fire-forming once fired cases in my .223AI, I get incipient separation pretty much at the high point indicated on the chart. (Virgin cases show no such separation when fire formed.)