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Jimro · August 22, 2011, 12:45 PM

First off 5.56 has a max pressure of 63,000 psi, and 223 Rem has a max pressure of 55,000 psi.

So you are unlikely to run into a pressure problem using 223 data even if you use 5.56 brass as long as you are shooting in a rifle that can handle 5.56 pressures.

Odds are you won't be able to stuff enough RL-15 into that case to cause any drama with a 55 grain bullet. BUT, it is ALWAYS smart to do a load workup with the components you will use in your rifle to check actual conditions. If your rifle had a tight chamber or short neck it could cause issues.

So back off from max and load up accordingly. Best accuracy should be with the powder right at the base of the neck, which should be well under 28 grains.

Jimro

August 22, 2011, 12:45 PM	#4
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	First off 5.56 has a max pressure of 63,000 psi, and 223 Rem has a max pressure of 55,000 psi. So you are unlikely to run into a pressure problem using 223 data even if you use 5.56 brass as long as you are shooting in a rifle that can handle 5.56 pressures. Odds are you won't be able to stuff enough RL-15 into that case to cause any drama with a 55 grain bullet. BUT, it is ALWAYS smart to do a load workup with the components you will use in your rifle to check actual conditions. If your rifle had a tight chamber or short neck it could cause issues. So back off from max and load up accordingly. Best accuracy should be with the powder right at the base of the neck, which should be well under 28 grains. Jimro __________________ Machine guns are awesome until you have to carry one.