5.56 vs .223 - Page 3

notamisfit6 · November 2, 2009, 08:41 PM

Quote:

ive got a s&w mp 15 and have no problem loading it with 5.56 .223 from current military issue to the cheapest that can be found and I have had no problems I dot see the diffrence

According to S&W's webpage, the M&P15 is in fact chambered for 5.56 NATO.

thallub · November 2, 2009, 09:03 PM

Quote:

The Nato round operates at an elevated pressure over the commercial cousin. It's around 60,000CUP where's the commercial is in the mid 50's.

Agree with most of what you said but I take issue with this.

Look at the US Army ammo data sheets. The M193 ball round generates 52,000 psi as measured by the transducer method. The M855 ball round generates 55,000 psi as measured by the transducer method. The SAAMI maximum average pressure for the .223 round is 52,000 cup which is 55,000 psi as measured by the transducer method.

http://www.scribd.com/doc/13027441/a...liber-firearms

Secondly, there are a dozen or so different .223/5.56mm chambers. A very good gunsmith tells me that he knows of no US maker who currently uses a SAAMI dimension chamber. Some NEF chambers are huge and some are even are out of round. Others are very tight. A guy who worked at H@R says that NEF re-ground their reamers.

These are the eight chamber dimensions that AR-15 barrels uses.

http://www.ar15barrels.com/data/223-556.pdf

There are issues with some of the LC .223/5.56mm ammo being sold on the civilian market. That stuff is being sold because it does not meet milspec. I have picked up once fired LC 05 and later cases whose necks are up to .035 longer than spec. This could ruin your gun and maybe your day if the gun has a tight chamber. I also have some very recently made US Army once fired cases that have no such defects.

LongRifles, Inc. · November 3, 2009, 10:52 AM

I'd like to add one additional caution to those who may consider running military ammunition in their guns.

Surplus ammunition becomes surplus ammunition for a reason. I realize it's often more affordable than the stuff down at the local sporting goods store, however a certain amount of liability and risk is going to have to be assumed if a guy goes the cheap route.

Personally I don't see the value but to each his own.

I do stand corrected on the pressure figures I quoted earlier. Sorry for passing bad info.

Chad

thallub · November 3, 2009, 01:25 PM

Quote:

Surplus ammunition becomes surplus ammunition for a reason. I realize it's often more affordable than the stuff down at the local sporting goods store, however a certain amount of liability and risk is going to have to be assumed if a guy goes the cheap route.

Exactly.

I am an EOD guy who has destroyed millions of rounds of defective Army ammo while in Army EOD and later as a civilian. The paperwork for destruction sometimes gave the reason for destroying that ammo. Some of that defective 5.56mm and 7.62mm ammo blew up guns and even injured troops.

Some folks have recently experienced blown out primers while using that recently made "surplus" LC ammo. Some if it was most likely fired in guns with tight chambers. However, some of it was fired in guns with 5.56mm chambers: There-in lies the problem.

qwman68 · November 3, 2009, 02:54 PM

my mini will shoot either but ive always been able to find .223 as cheap as surplus.even though it will shoot surplus i just stick with the .223.if i really needed to use surplus that would be a diffrent story.

TrafficTech · November 3, 2009, 03:46 PM

Quote:

ive got a s&w mp 15 and have no problem loading it with 5.56 .223 from current military issue to the cheapest that can be found and I have had no problems I dot see the diffrence

Same thing here. I've never had any problems.

From S&W web site...........

Model: M&P15
Caliber: 5.56 mm NATO / .223
Action: Gas Operated Semi Automatic
Capacity: 30 Rounds, 5.56 mm or .223
Overall Length: 35" Extended / 32" Compacted
Stock: 6-Position Telescopic
Forend: Thermo-Set M4 Handguard
Sight Length: 14.75"
Barrel Length: 16"
Barrel Twist: 1 in 9"
Weight (No Mag): 6.74 lbs.
Trigger Pull: 7 lbs. (approx.)
Upper/Lower Material: 7075 T6 Aluminum
Barrel Material: 4140 Steel
Chromed Components: Barrel Bore, Gas Key, Bolt Carrier
Receiver and Barrel Finish: Hard Coat Black Anodized
Front Sight: Adjustable Post
Rear Sight: Adjustable Dual Aperature

MLeake · November 3, 2009, 03:50 PM

... your rifle's manufacturer has specifically designed the rifle to chamber and handle 5.56mm.

Not all manufacturers do that; so not all specification sheets list 5.56mm. The OP's question had to do with whether his rifle was ok for 5.56mm.

When I bought my AR, I deliberately narrowed the list to those that listed 5.56mm in the specs.

Has somewhat to do with pressure, but more to do with chamber shape and its impact on how pressure is handled and pressure wave is created. See Long Rifle's post 8 up from yours.

November 3, 2009, 03:50 PM	#57
MLeake Senior Member Join Date: November 15, 2007 Location: Outside KC, MO Posts: 10,128	Traffic Tech... ... your rifle's manufacturer has specifically designed the rifle to chamber and handle 5.56mm. Not all manufacturers do that; so not all specification sheets list 5.56mm. The OP's question had to do with whether his rifle was ok for 5.56mm. When I bought my AR, I deliberately narrowed the list to those that listed 5.56mm in the specs. Has somewhat to do with pressure, but more to do with chamber shape and its impact on how pressure is handled and pressure wave is created. See Long Rifle's post 8 up from yours.

November 3, 2009, 10:52 AM	#53
LongRifles, Inc. Senior Member Join Date: October 21, 2009 Location: Black Hills of S. Dakota Posts: 195	I'd like to add one additional caution to those who may consider running military ammunition in their guns. Surplus ammunition becomes surplus ammunition for a reason. I realize it's often more affordable than the stuff down at the local sporting goods store, however a certain amount of liability and risk is going to have to be assumed if a guy goes the cheap route. Personally I don't see the value but to each his own. I do stand corrected on the pressure figures I quoted earlier. Sorry for passing bad info. Chad

November 3, 2009, 02:54 PM	#55
qwman68 Junior member Join Date: May 10, 2009 Location: Crimson Tide Country Posts: 359	my mini will shoot either but ive always been able to find .223 as cheap as surplus.even though it will shoot surplus i just stick with the .223.if i really needed to use surplus that would be a diffrent story.