The Firing Line Forums - View Single Post

HiBC · June 24, 2011, 02:39 PM

krmcne: I can't tell you whether it is safe to shoot your loads.There are too many variables.And,I'm not THE guy to tell you.
Here is something more to work with.
As the powder ignites,and pressure goes up,The case expands and it grips the chamber wall.The forward part of the case does not slide back.What happens is your case stetches back to the bolt face.Unfortunately,it does not pull the stretch from the full length of the brass.The stretch occurs at approximately the chamber mouth.As the brass is pulled longer,it gets thinner.
The visual part of the thinning occurs inside the cartridge case.Some reloading manuals discuss case stretch and stretch rings.Look.Even if you have only loaded this brass a couple of times,hacksaw one lengthwise and you will likely see the brass has thinned in a ring about 3/8 to 1/2 in fwd of the base of the case.
There is a way to use a bent paper clip to feel for stretch rings as a brass inspection procedure.
A noticable stretch ring is a weak spot in a bad place.The brass is all that keeps the 50,000psi hot gas where it belongs.
The shoulder of a 243 establishes the headspace.You do want your die to set back the shoulder of a round fired in your rifle about .002.That will allow you to easily close the bolt,yet minimize case stretch.
Once you start that,then your primers speak a different language.Then you can get a little nervous about flattened primers.

June 24, 2011, 02:39 PM	#16
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,286	krmcne: I can't tell you whether it is safe to shoot your loads.There are too many variables.And,I'm not THE guy to tell you. Here is something more to work with. As the powder ignites,and pressure goes up,The case expands and it grips the chamber wall.The forward part of the case does not slide back.What happens is your case stetches back to the bolt face.Unfortunately,it does not pull the stretch from the full length of the brass.The stretch occurs at approximately the chamber mouth.As the brass is pulled longer,it gets thinner. The visual part of the thinning occurs inside the cartridge case.Some reloading manuals discuss case stretch and stretch rings.Look.Even if you have only loaded this brass a couple of times,hacksaw one lengthwise and you will likely see the brass has thinned in a ring about 3/8 to 1/2 in fwd of the base of the case. There is a way to use a bent paper clip to feel for stretch rings as a brass inspection procedure. A noticable stretch ring is a weak spot in a bad place.The brass is all that keeps the 50,000psi hot gas where it belongs. The shoulder of a 243 establishes the headspace.You do want your die to set back the shoulder of a round fired in your rifle about .002.That will allow you to easily close the bolt,yet minimize case stretch. Once you start that,then your primers speak a different language.Then you can get a little nervous about flattened primers.