223/556

[kestak]

Greetings,

I have been reloading for a few years and thanks to this website and a few others I did not blew up myself...yet...

Anyway, I have a VERY special and stupid question:

I have been reloading .223/556 for a while and my load is 25.1 grains of Ramshot TAC under 55 FMJ or SP Hornady. I am using FC, PPU, RP, PMC and LC brass.

I did not notice anything wrong using any of those brass headstamps. All my ARs, my FS2000 and SIG 556 are 556 barells and chambers.

My question is 2 parts:

a) Do I generate more pressure with the LC brass that is 556 than the other brass that is 223?

b) Does that mean when I shoot LC brass I am shooting 556 and when I shoot the other brass I am shooting 223? In my reloading books, there is data only for 223. They don't make a difference.

Thank you

 

[X-Rap]

I use all kinds of brass for the same loads and really can't see any measurable difference with the thicker LC brass. My load is the highest in the Nosler book and most references warn of the pressure elevations for the heavier brass but I have not seen it in any of my AR's, bolts, or single shot rifles or pistols.
This is only what I have witnessed but in a dozen or so guns that I am familiar with there are no visible effects with the hand loads or factory 223 or 5.56.
As with all shooting, approach loads with caution.

 

[ants]

'LC brass thicker' may be a myth

Ammo Oracle did a survey of military and commercial brass, measuring internal volume and weighing each case.

LC did NOT have thicker brass than commercial, nor smaller interior case volume, contrary to posts you read on the Internet.

You'll have to do some searching on THR and other locations, I don't have a link handy to that particular Ammo Oracle report.

 

[rcmodel]

Scroll down about 1/4 way on this page to Brass--New and Once-Fired.

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

As you can see, there is quite a difference in case weight between different brands.

The heavier a case is, the less internal volume, or capacity it has.
That makes higher pressure.

But as you can also see, not all 5.56mm brass is heavier then all .223 brass.

So no, you are not necessarily running higher pressure, or even as much, in any 5.56mm brass then the same load would produce in some .223 brass.

rc

 

[pcg8r]

If you can throw a consistant charge, load to near case capacity & see if there is a visual diff between cases. I think 25 grains of Varget is something like a 96% filled case.

 

[Randy1911]

The 5.56 is loaded to a higher pressure than 223. The reason that there is no data is because it is a military only load data. And the military won't tell you. This might be helpful, but use at your own risk.http://www.frfrogspad.com/miscellq.htm#duplicate

 

[steve4102]

My question is 2 parts:

a) Do I generate more pressure with the LC brass that is 556 than the other brass that is 223? No, yes, maybe. No way to tell without real pressure testing equipment. You can do a simple case volume test though. Measure the case capacity of a fired case,cases in grains of H20. The higher the volume the less pressure.

b) Does that mean when I shoot LC brass I am shooting 556 and when I shoot the other brass I am shooting 223? In my reloading books, there is data only for 223. They don't make a difference.
NO!

I am with the posts above, LC brass does not have less case capacity and automatically increase pressures in the 223, the 308 and 30-06 yes, maybe, the 223 not .