Is it worth trimming IMG 5.56 brass for reloading for a .223 DPMS upper?

[MCMXI]

I'm in the middle of trimming 1000 .223 cases down to 1.750" with the intention of reloading 1000 rounds for "storage". While rummaging in my garage, I came across about 200 or so IMG 5.56 once-fired cases (green ring around primer). The brass has an annealed case mouth, the primer doesn't appear to be crimped, and I was able to run a couple of cases through the .223 full-length resizing die without incident. I did an internet search on IMG and 5.56 brass. I discovered that IMG stands for Industria Militare De Guatemala and the case is headstamped IMG 5.56 92. I couldn't find any information on this board about IMG or reloading 5.56 brass. I've read that 5.56 (military) brass is often thicker than "civilian" brass which reduces the internal volume. Is this good brass? Any ideas, thoughts, suggestions, opinions, etc?

Thanks.

 

[ants]

Yes, you can load it safely. I've loaded IMG just like any other 5.56/223 brass. If you want to experiment, fill the IMG brass with alcohol or water, and pour it into a commecial 223 case (make sure every drop transfers). You can see the difference in case volume. It is very small. If the difference concerns you, drop the powder charge by a couple tenths.

I've used a graduated burette to measure military vs. commercial, and I find that some milsurp cases have MORE capacity than commercial, some have less. Also, military cases with the same headstamp but different years can differ in capacity. And no two commercial manufacturers make the same case volume either.

Go here http://www.6mmbr.com/223Rem.html for an interesting comparison, including case volume and weight. Just keep in mind that many 5.56/.223 manufacturers change their dimensions from time to time, so the data listed on that site may not be current any more.

 

[ants]

And furthermore...

And go here http://m4carbine.net/showthread.php?t=6642 for a nice comparison of AR features. You can see what chamber your DPMS barrel has. If you need a resource for comparing 5.56 chambers versus commercial .223 Rem, go here http://www.ammo-oracle.com/body.htm#diff for some interesting info (although this web site is getting a little old, and some of the text and graphics load poorly). The first part of the article has a graphic diagram of the differences between the chambers, and you will probably become much more comfortable making decisions on brass and other components.

 

[MCMXI]

ants, thanks so much. I completely forgot about the 6mmbr site and it didn't pop up in a Google search. I was interested to see that the other three case manufactures that I'm reloading, namely WCC, Remington and Winchester, have similar H2O capacities compared to IMG ... 30.5, 30.4, 30.1 and 30.1 grains respectively. The site says of IMG brass "This is good stuff, made on U.S. OLIN machinery exported to Latin America." so that's good news. Once I've trimmed all four brands of cases, I'll do some H2O capacity tests of my own. They weigh the case full of water it seems rather than measure the volume. That's a lot easier and possibly more accurate for me. I also looked at the other links that you posted and according to the "ammo-oracle" DPMS chambers are 5.56 ... that's interesting but it's not a deal breaker. It's good to know that I could safely shoot 5.56 rounds in my DPMS upper though. Basically I just wanted to find out if the IMG brass is decent stuff and if I'll have any problems with the capacity. I don't want to spend the time prepping hundreds of IMG cases only to find that the stuff is rubbish.

Thanks for the help.