Head space comparator gage

[JScott]

(04-05-2015, 10:18 PM)rdhem2 Wrote: With the gauge protruding so far through the base (?) what do you measure? 

rd, here a couple of pics/illustrations that show what the gage measures.

Head space is the distance from a datum in the chamber to the breech face.  In this instance it is the distance from the cartridge shoulder to the breech face of the Contender pistol.  If you have too much head space or "slop" the cartridges can stretch excessively or even worse they may fail to fire.

   

In this picture you can see the cartridge in the chamber of the barrel.  The comparator gage sits on top of the barrel and the stem of the indicator rests on the head of the cartridge.  By first resting the comparator gage on a flat surface and setting the bezel to zero it will tell you how much the cartridge case head is above or below the end of the barrel.


  Picture4.jpg (Size: 9.19 KB / Downloads: 139)

I wanted to set the head space to a maximum of 0.002" for my Contender.  I measured the barrel to frame gap with feeler gages and came up with a gap of 0.010".  I set my dies and reloaded the ammunition so that the cartridge case head protruded above the face of the barrel 0.008" to 0.009".  I have fired 3 of these rounds and they all look great so it appears that my gage is working!

I hope this explanation helps.