Using Hornady Headspace Gauge to determine proper .223/5.56 headspace

[outerlimits]

I've been following the two similar threads, this one and the one by Clay Autery. It seems that all the tools available are making people question what the heck is to be done.

I've been an R&D machinist for over 40 years. This isn't rocket science, and a couple thousandths of space won't have AR parts strewn over the countryside.

I've been playing with AR's since before the plethora of parts that we now have available. I've machined barrel blanks and chambered them for AR's. Not just tighten a barrel nut and said that I've "built" an AR.

I use a Clymer .223 Rem Go gage to set my dies. I use a bushing, to take a measurement over the gage, the inside diameter doesn't mean squat, as long as you use the same bushing for all measuring. I set my sizing die to bump the shoulder back .002 under the dimension that I got from the chambering headspace gage, and size all my brass that way.

One of my AR's has a barrel that I machined and chambered, and the bolt would just rotate into battery when it was new. The brass fits in all 5 or 6 AR's in the safe, no issues.

Now, not trimming brass, and mushrooming the shoulder slightly has caused more problems than not bumping the shoulder back enough.

I hope this helped.

Take heed to what Dan is saying. He knows wtf he's talking about.

[bigedp51]

Kasteel

It doesn't matter what my measurements were with my Hornady gauge, with your gauge comparing readings could be different. I do not have a GO gauge to give you a "zero" reference point.

Measure the length of a unfired Lake City cartridge and measure the length of your fired cases and reach a compromise. I stated my loaded cases are .001 to .002 longer than factory loaded rounds.

You will need to find your own minimum shoulder bump for the cases you are shooting and the pressure you load them to. Commercial cases are not made to military standards and military Lake City cases are made to higher standards to withstand longer and fatter chambers. Each brand of brass will have different spring back rates and corresponding shoulder bump.

I didn't over think the matter, the Redding custom shell holder .002 taller than the RCBS shell holder made the cases the same length or slightly shorter than factory loaded ammunition. The Redding .004 shell holder resized the cases on average .002 longer and the .006 shell holder didn't give me enough head clearance.

When your using mixed range pickup brass for practice you want the cases at the small end of tolerances. If your loading brand new Lapua brass for competition you might want them longer.

I cant tell you what will work in your rifles and that is up to you to find out with your brass, powder and dies.

Edited August 26, 2013 by bigedp51