Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Possible Pressure Signs with factory Loaded Ammo?
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Canadian Bushman" data-source="post: 1077669" data-attributes="member: 41122"><p>Oil in a chamber prevents the case from grabbing the chamber walls and thrust the case back against the bolt much harder than a dry chamber would allow. This will put lots of force on the head showing all the signs of high pressure. </p><p></p><p>When you mic a case head to identify pressure signs you do it right in front of the extractor groove. I use blade mics as to pinpoint the area im measuring, and i also measure the extractor groove as this part of the case is unsupported by the chamber and is a rough representation of the force the case head is exerting against the bolt. Typically growth of >.0005" is indicative of high pressure, ( or excessive headspace). Usually this is confirms with loose pockets after only a few firings. Each case should be measured multiple times around the circumference before and after its fired. If you are not measuring the same case the process is a wash. </p><p></p><p>I think the measurements you took were too far forward. </p><p></p><p>Headspace is a fickle beast. There is a spec for the cartridge and a spec for the chamber. If the smith cuts the chamber to the high, and the brass is sized to the low, everything is in spec, and you still have excessive headspace. This is a common condition for factory rifles and is not major problem if identified. Just an inconvenience. </p><p>If this condition is present its best to fireform the cases to the chamber with a ff load or even a starting load in most cases before a full pressure load is run. This will greatly preserve your brass. </p><p></p><p><a href="http://www.saami.org/pubresources/cc_drawings/Rifle/300%20Remington%20Ultra%20Magnum.pdf" target="_blank">http://www.saami.org/pubresources/cc_drawings/Rifle/300 Remington Ultra Magnum.pdf</a></p></blockquote><p></p>
[QUOTE="Canadian Bushman, post: 1077669, member: 41122"] Oil in a chamber prevents the case from grabbing the chamber walls and thrust the case back against the bolt much harder than a dry chamber would allow. This will put lots of force on the head showing all the signs of high pressure. When you mic a case head to identify pressure signs you do it right in front of the extractor groove. I use blade mics as to pinpoint the area im measuring, and i also measure the extractor groove as this part of the case is unsupported by the chamber and is a rough representation of the force the case head is exerting against the bolt. Typically growth of >.0005" is indicative of high pressure, ( or excessive headspace). Usually this is confirms with loose pockets after only a few firings. Each case should be measured multiple times around the circumference before and after its fired. If you are not measuring the same case the process is a wash. I think the measurements you took were too far forward. Headspace is a fickle beast. There is a spec for the cartridge and a spec for the chamber. If the smith cuts the chamber to the high, and the brass is sized to the low, everything is in spec, and you still have excessive headspace. This is a common condition for factory rifles and is not major problem if identified. Just an inconvenience. If this condition is present its best to fireform the cases to the chamber with a ff load or even a starting load in most cases before a full pressure load is run. This will greatly preserve your brass. [url]http://www.saami.org/pubresources/cc_drawings/Rifle/300%20Remington%20Ultra%20Magnum.pdf[/url] [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Possible Pressure Signs with factory Loaded Ammo?
Top