What is brass weight difference...

[jjrothWA]

between brass marked 5.56 with NATO cross and those marked .223Rem?

Normally any 5.5.6 is thicker and made for Semi & Full-Auto cycling, commercial is lighter and thinner.

My question come from a 21" T/C Contender barrel that I use to pop some suspect primers, I chambered a mil-spec case and after firing the
case was stiff to remove and put a "bow"[temporarily] in the extractor, as it tried to push the case out.
I relieved the strain and popped the case out using a 1/8" diameter rod.

Am getting a spare replacement extractor but just want to get a weight to reference if the case in uncertain.

I think PMC uses the same case for mil=spec and commercial, true or false.

Thanks!

CAN'T WAIT for NOON!!!!

[Major Tom]

Generally, heavier brass meant less case capacity. Reloaders would use less powder in heavier cases.

[p246]

Were they reloads. If new primer crimped 5.56 it takes some over pressure to pop primer. If they are well used cases with swaged or reamed primer pockets they may just be worn out.

[bigedp51]

The images below are from http://www.accurateshooter.com/cartr...223rem/http://

Lake City and commercial contract 5.56 for the military is made from harder brass and the cases are not thicker like 7.62 LC brass. The harder brass came about after the 1968 Congressional Hearings on the M16 jamming problem and was just one of the fixes. As you can see below the majority of .233 and 5.56 cases fall into a close case capacity.

I have Quickload and for the .223/5.56 it defaults to a case capacity of 28.0 grains of H2O and as you can see Lake City brass has a case capacity of 30.6. This difference of 2.6 grains of H2O case capacity can cause a 6,000 psi chamber pressure difference. "BUT" as you can see the American made cases vary little in capacity.





Below "How hard is your .223/5.56 brass"

http://bulletin.accurateshooter.com/...ardness-tests/

I'm going to take a WAG and say if your 5.56 cases were fired in a machine gun with a larger diameter chamber your problem is brass spring back. Meaning after full length sizing the case tried to spring back to its fired size, and the case diameter after sizing did not allow your fired cases to "spring back" from your chamber walls.

I buy a lot of once fired Lake City 5.56 brass for my two AR15 rifles and a Bolt action Savage .223. These once fired LC 5.56 cases are resized once with a small base RCBS AR Series die and thereafter resized with a standard .223 die. It is recommended that a resized case for a semi-auto be .003 to .005 smaller in diameter than its fired diameter.

Bottom line cases fired in one chamber can sometimes cause problems when full length resized and fired in another chamber. And if the cases are fired in a even fatter diameter chamber or worse a machine gun chamber .002 to .003 larger in diameter you "WILL" have problems with extraction. And your T/C Contender does not have the primary extraction force like a bolt action and depends on your extractor spring to break the case free of the chamber walls and eject the case.

NOTE, before buying a small base die try pausing at the top of the ram stroke when sizing a few cases for 4 to 5 seconds. This pausing will reduce brass spring back after sizing, this pausing lets the brass know who is the boss and to stay put after sizing. Many times this will fix the problem if the cases were not fired in a fat chambered machine gun. If this does not work a small base die will be necessary. Just remember we live in a plus and minus manufacturing world and that chambers and dies "DO" vary in size. Example I have a standard Lee full length die that sizes the body of the case smaller in diameter than my small base dies do.

Trust me, I have a "few" .223/5.56 dies and my Lee and Lyman dies are not in the photo. It also helps to work in a Sporting Good store and have a good discount to satisfy my resizing die OCD.
I'm retired and have nothing to do and all day to do it and spend too much money on dies.