5.56 casings

[Janes]

When I was at the gun range today I picked up some 5.56 casings. All of the casings are longer than my 223 so should I trim them the same length? Also when I reload them should I use the same amount of powder as when I reload the 223?

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[DieselScout]

What is your rifle chambered in? How much is "longer"?

 

[My 3 sons]

First is your rifle chambered for 5.56 or .223?
The reading I've done says there is a difference in the shoulders between them. This is why it is recommended to not fire 5.56 through a .223 chamber. I've never owned a .223 weapon only 5.56 so I'm sure others will have more info than me.
As far as trimming and loading I size and trim my brass for both the same. You can see some variation in case volume from one brand to another though especially if you are loading hotter loads.
The first rule I've always seen the old timers give is start slow and work it up.

 

[Janes]

My gun is chambered for the 5.56

 

[DieselScout]

My gun is chambered for the 5.56

Is the length out of spec for a 5.56?

 

[Janes]

I haven't found any spec. For the 5.56

 

[DieselScout]

I haven't found any spec. For the 5.56

Quick Google search says 1.740"-1.760"

 

[AMProducts]

Guys... .223 and 5.56 have identical cartridge dimensions, the only difference is the pressure tolerances, 5.56 pressures are always higher than for .223. The major physical difference between the two is the 5.56 chamber has a looser throat to lower the engraving force of the bullet.

So to answer your question concisely, trim your brass to the same length!

 

[Janes]

These are a little longer than 1.760. So should I trim all the same length as my 223 so the bullet would be seated same as the 233

 

[circlepranch]

You will notice different info in reload manuals, trim cases to 1.75 then seat bullets any where from 2.20 to no more then 2.26. I have settled on middle ground of 2.23 plus it easy to remember

 

[AMProducts]

I trim to 1.745" and load to an OAL of 2.245". 2.26" is the max COL, and usually if you're longer than 2.255 you can have feeding issues in AR's and some rounds won't fit inside the magazine or won't feed reliably.

I cut all brass to the same length so when I'm crimping it I get a nice uniform crimp.