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Old July 19, 2006, 06:28 PM   #13
Buckythebrewer
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Join Date: April 15, 2006
Location: Jefferson, ME
Posts: 700
Texan ,That is the rcbs gauge I was talking about..The thing that I find is I use a case gauge by feel with the fingers to know if my ammo is in the safe ball park,,But what I notice is its hard to use a regular case gauge by feel to know exactly what the before and after measurements are.I use BOTH because the regular case gauge(I have a $12 dollar wilson)Is fast to check my ammo,And the rcbs is more precise for adjusting my Sizing die(for my accurate long range ammo).Its hard to go by feel and tell how many thousandths difference there is with a simple case gauge, but with the rcbs gauge it is very easy.

Say you measure from the head to the shoulder on your unfired factory ammo with the rcbs comparitor mic and it reads .004 under saami minimum standard,,Then you fire the round and it reads .001 OVER saami minimum standard.Your goal for a semi-auto 223 is to size at least .004 smaller than your chamber for safety(You wan't that bolt to lock-up with no problems) You can adjust your dies, and read how far your adjusting them with the rcbs comparitor mic by measureing your case while you adjust your dies( a little at a time) until it bumps the shoulder back to around .003 under saami minimum standards( sorry if I said that confusingly ).

That way your brass does not have to violently expand back to fit your chAMBER AS BAD.It usually makes a more accurate cartridge as well as make your brass last longer.At the very least get the cause gauge and drop your ammo in it to make sure your in the ball park,But I highly recommend the rcbs comapritor mic to go along with it . I will admit I have bumped the shoulder only .002 smaller than my chamber and it feeds fine and shoots great @ 625yrds but technicly it is unsafe to do so(and it can lead to ar15's blowing up),,You should size .004 or so under your chamber size to be safe.good luck

The rcbs gauge reads from the head to the datum line on the case(near were the shoulder ends on the outside of the case),I don't think there is an accurate way for you to measure that with a dial indicator but I could be wrong..
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