223 to 300 case headspace / gaging problem

[newman0912]

Hi, first post here. Thanks in advance for your help.
I've got the Harbor Freight cutoff saw with a fixture to cut down 223 brass. I'm only using brass that's on the 'acceptable wall thickness' list.
I've got two sizing dies; RCBS 'AR' SB sizing die and the Lee full length sizing die.
I've also got the Lyman case headspace/length gage.

Cases are rough cut to about 1.370, deburred, lubed, and sized.
I've tried both sizing dies but the end results do not fit the Lyman case gage.
I've followed the instructions on both sizing dies which is to screw die into press until it touches the shell holder, then turn another 1/4 turn.

In both dies, the resulting cases are all very consistent, they do not 'plunk' into the die and seat between the low and high marks. Rather, they are all sitting up quite a bit higher than the high edge of the gage.

I'm not sure what to do next. Thanks!

[TRshootem]

After the chop of the .223 case you need to trim 1.363 as max. I do all mine at 1.360. Once that is done, pressing the case into the sizing die will result in correct headspace once you have adjusted the die down to headspace in your gauge. Try not to have the finished case drop more than say .002-.003 thousands/inch below the very top of the gauge. It takes just a little fiddling to get it right.