Overpressure signs?

[JDHasty]

Not to try and derail the thread.  But what's does case web expansion really tell you about over pressure?  I have a very tight cut chamber and experience slight bolt lift and only have 2.5 thou expansion from factory brass.  I loaded a 300wm hs precision for a friend and he has zero signs of pressure but has 9 thou expansion?

Brass varies in hardness depending upon brand and then even within the same brand.  You want to measure an unfired case and then measure a fired case of known pressure if at all possible. 

[hogslayer]

I get that brass has different hardness.  This was done between Hornady brass on the 300, and norma brass on the 28.  I was more curious how web expansion can dictate pressure since i had 9 thou expansion with no sticky bolt.  Then have 2.5 on a tighter cut chamber and have sticky bolt.....

[JDHasty]

I get that brass has different hardness.  This was done between Hornady brass on the 300, and norma brass on the 28.  I was more curious how web expansion can dictate pressure since i had 9 thou expansion with no sticky bolt.  Then have 2.5 on a tighter cut chamber and have sticky bolt.....

I have a really good article that was in Precision Shooting photocopied and tucked in the pages of one of my dozens of loading manuals, but could not find it last night.

In the mean time this is a short discussion from Hodgdon's website:  http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads

Using a blade micrometer that measures in ten thousandths (.0001"), new, unfired cases can be gauged before and after firing to determine reasonably accurate maximum loads. Micrometers measuring in thousandths (.001") are insufficiently accurate to perform these measurements, and should not be used. Previously fired cases cannot be used accurately due to various levels of brass hardening. Measurement is taken just ahead of the extractor groove on the case head and must be taken at the same place on the case before and after firing. By placing a small mark on the case head – entering the cartridge in the chamber with mark at 12 o’clock – a consistently accurate measurement can be taken with each firing.

[high country]

I get that brass has different hardness.  This was done between Hornady brass on the 300, and norma brass on the 28.  I was more curious how web expansion can dictate pressure since i had 9 thou expansion with no sticky bolt.  Then have 2.5 on a tighter cut chamber and have sticky bolt.....

Pull your measuments from the case just in front of the extractor groove. That area is unsupported and will show you expansion. If it grows .009" the primer will fall out.

[Magnum_Willys]

On belted brass I find that on sticky loads belt grows by .002 or more.  Same results show just above belt.   I have a baseline measurement for my brass and if belt/web grows by more than .002 to .0025  it goes into oversize pile for scrap or play only.

No need for anything other than a blade micrometer in my experience with large magnum cases.