A little help on headspace please

[mnhntr]

I am measuring my spent .223 brass and getting 1.451-1.455 at the Datum line and the Lee manual is showing 1.467 for .223 headspace. Is it short because it is fired out of an AR or is it something else?

 

[Suasponte]

Are you using the Hornady Gage? If so, the is a bevel on the inside of the tool that will make it appear that you
are off.



Terry

 

[mnhntr]

Thanks for the tip. That is exactly the issue.

 

[FLIGHT762]

To get an Idea of near minimum SAAMI headspace when using the Hornady gauge, you can take the measurements off of some factory loaded 223/5.56 NATO. Those measurements will be at or slightly below SAAMI minimum. The other way to determine how much bevel you have on your .330" insert, you can get a .223 Rem. Go gauge and measure it.

My .400" Hornady insert for the 308 Winchester measures 1.611" on a 308 winchester 1.630" Go gauge, indicating I have a .019" bevel on my .400" insert. This tells me when I use my .400" insert, 1.611" is SAAMI minimum.

With my Hornady .330" insert for .223 Remington, I get measurements of 1.462"- 1.465" from fired cases out of my AR-15's. I f/L resize these cases down to 1.458"-1.460" which will chamber in all of my AR-15's. In my .223 Remington 700 Factory Varmint rifle, fired cases measure out to 1.455"- 1.456".

I measured an array of Factory loaded .223 and Military 5.56 ammo and came up with shoulder datum measurements between 1.453"- 1.456".

Hope this helps.