Head space

[andrewst35]

Quick question on headspace. Does headspace change oal of the case itself or just the shoulder measurement?

[Con]

Just shoulder measurement.
Cheers...
Con

[felkebg]

I am using a Mo's but living with + or - 2 units on the head space measure.

[earl39]

I know this is an old thread that has been brought back up but after reading all of it i have found one flaw that has not been addressed. To prevent case head separation the case needs as much support as it can get as in as small of space as possible between the bolt head and the barrel. No where in all of this thread was the question raised as what to do if the chamber was cut short. Lets say the camber was cut 10 thousandths short. Now you have a gap of no less than 11-13 thousandths from the end of the bolt head to the barrel and odds are it is greater than that. It should be noted that everyone should double check the chamber before installing a barrel. Yours may be cut short or it may be long and need to be returned. You can determine this gap by putting the gage/fired and sized case in the chamber and measure the part that protrudes. Subtract from that number the distance from bolt face to front of the bolt and you have the air gap or unsupported part of the brass when head space is set snug on that gage/brass. The less the better. A zero or negative number is not good as that means you have too deep of a chamber. The unsupported section can vary by cartridge due to brass thickness and pressure ratings of said cartridge but the smaller the section is the better. Now you ask how much is too much? I for one do not have an answer but i shoot for the least amount that i can get and still not have the bolt face rubbing the barrel face when i close the bolt. In my case it is 2-5 thousandths. I am not saying to set your barrel up this way just to double check your chamber before you get started.