headspace

ontarget7

Well-Known Member
Joined
Jul 25, 2021
Messages
151
Location
Utah
I feel headspace is used two ways and both are appropriate but one is static per say measurement and the other a dynamic if that makes sense.
 

RuninL8

Well-Known Member
LRH Sponsor
Joined
Feb 20, 2019
Messages
53
Location
Columbia, mo
In my mind, headspace is gauging the length of the chamber from datum to bolt face. Thanks to the internet "headspace" now means 2 different things, one of which is not correct. Cartridge fit is not headspace. Only the distance from datum to bolt face is. Brass is not made to the same tolerances that hardened steel gauges are. Brass is malleable, it can be shaped easily. Upon firing the brass 'swells' to me the chamber walls and when pressure drops, it contracts. Any material that can move that much is not a "gauge".
You are absolutely correct. Once a chamber is cut with a reamer, the headspace is set. All a shooter can do is measure his/her her brass to set how much brass flow they want with each shot.
 

shortgrass

Well-Known Member
Joined
Mar 31, 2010
Messages
3,244
Location
Weatherford, Oklahoma
The 'other' important thing when swapping barrels that are 'take-offs' or originally fit to another action, is the length of the treaded tenon. That length, provided the headspace is correct, determines how much of the cartridge case (how long the gap is between the end of the barrel and the end of the bolt ) is NOT actually in the chamber. A certain amount has to 'stick out', but not more than necessary for recessed bolt face/extraction. You don't want the end of the bolt touching the barrel.
 
Last edited:

oneeyejohn

Well-Known Member
Joined
Nov 25, 2014
Messages
87
Location
AR.
I have had about 4 rifles with barrel replacements that resulted in sizing dies that would not push back the datum line of a twice fired case. I simply ground off the bottom of the Sizing Die until it would push back the datum line .005. Then I can adjust the die to push the datum line back .002 to .003 for the next load. I also anneal after the third load.
 

shortgrass

Well-Known Member
Joined
Mar 31, 2010
Messages
3,244
Location
Weatherford, Oklahoma
And I would fire form some brass with bullets seated out.
What Bill says makes sense.. By jamming the bullet, when a 'long' chamber exists, the brass stretches at the shoulder end, not the head. Reload from those fireformed with the desired shoulder 'bump'. All this must be taken into reason, of course. If the chamber was groosly long, it'd need fixed to be safe.
 

MNbogboy

Well-Known Member
Joined
Jul 14, 2009
Messages
954
Location
Northern MN
Too much headspace can and is most often the cause of light primer strikes. I try for .002 max using "scotch" tape on the head of the headspace gauge is my no-go gauge. Tape is approximately .002 thick.
 

shortgrass

Well-Known Member
Joined
Mar 31, 2010
Messages
3,244
Location
Weatherford, Oklahoma
Too much headspace can and is most often the cause of light primer strikes. I try for .002 max using "scotch" tape on the head of the headspace gauge is my no-go gauge. Tape is approximately .002 thick.
I think 'crystalgaleguy' is taking about factory take-offs. In which case, there not much use in putting too many $$$ into one just to say the headspace is GO + .002.
 

MNbogboy

Well-Known Member
Joined
Jul 14, 2009
Messages
954
Location
Northern MN
I think 'crystalgaleguy' is taking about factory take-offs. In which case, there not much use in putting too many $$$ into one just to say the headspace is GO + .002.
Factory take offs were not necessarily chambered correctly the first time at the factory. Production pressure has literally forced too many shortcuts to doing things the correct way. I've checked go-gauge protrusion on many take offs. Some are ok while some chambers appear too deep. Dr
Track and rechamber will often cure what was done wrong the first time.
Virgin brass and tape is not a substitute for go-no go gauges just to save $30 to $65 on a budget rebarrel. You can't do a job correctly without the proper tools.
 

MNbogboy

Well-Known Member
Joined
Jul 14, 2009
Messages
954
Location
Northern MN
One of the biggest changes I've made to accurately bumping shoulders back on fired cases is an annealing program that is done at every firing. Annealing the full shoulder and neck as well as about an eighth inch down from the shoulder body junctiont, helps make the bump match the die setting every sizing. I often have used the chamber reamer to modify the Hornady tool aluminum inserts for better datum to case head measurements. The "bumped"brass can easily be matched to fired brass
 
Top